February 22, 2012

Nutritional biochemistry

Why Weight Watchers is actually a low carb diet

Read Time 12 minutes

Invariably I get asked the question, “If carbohydrates are so bad, why did [so-and-so] lose weight on the [such-and-such] diet?”, where “such-and-such” diet is not a “low-carb” diet. Obviously, this is an important question and a pretty complex one.

There are several layers to this and, frankly, there are some things we can’t fully explain – I’ll always acknowledge this. That said, many of the successes (at least weight-wise, though hopefully by now you realize there is much more to health than just body composition) of popular diets can be explained by a few simple observations. Above is a list of this year’s most “popular” diets, according to Consumer Reports. Popularity, of course, was determined by a number of factors, including compliance with current government recommendations (sorry Atkins), number of people who have tried the diet, and reported success on the diets. So it’s actually quite misleading when the report says it’s reporting on the “most effective diets.”

Keep in mind the average American (i.e., at baseline) consumes about 2,500 to 2,700 calories per day (different sources, from NHANES to USDA will give slightly different numbers for this, but this range is about correct), of which about 450 grams (about 1,750 calories worth or about 65% of total caloric intake) comes from carbohydrates. You can argue that those who are overweight probably consume an even greater amount of carbohydrates. But for the purpose of simplicity, let’s assume even the folks who go on these diets are consuming the national average of approximately 450 grams of carbohydrate per day (in compliance with governmental recommendations, as a percent of overall intake).

Take a look again at the figure below, which shows you how many calories folks are consuming on each diet and, more importantly, where those calories come from. [It’s not actually clear to me how Consumer Reports was able to figure out exactly how much folks eat, beyond self-reporting or diet-book recommendation, mind you. In other words, these numbers could actually be wrong, but it’s what we’ve got for now.]


Why diets work

[Note: in a more recent (2017, consumerreports.org) analysis, the following categories were included: initial weight loss, maintenance, calorie awareness, food variety, fruits and vegetables, and exercise.]

You’ll note that people on these diets, including the strictest low-fat high-carb diets, significantly reduce their total amount of carbohydrates (therefore reducing the amount of insulin they secrete). Even the Ornish diet, which is the most restrictive diet with respect to fat and most liberal with respect to carbohydrates, still reduces carbohydrate intake by about 40% from what people were likely eating pre-diet.

The reason, I believe, most of these diets have some efficacy – at least in the short-term – is that they all reduce sugar and highly refined carbohydrate intake, either explicitly or implicitly. No one on the Ornish Diet or Jenny Craig Diet is eating candy bars and potato chips, at least not if they are adhering to it. Hence, these diet plans do “clean up” the eating habits of most folks.

Someone made a great point in response to my post on why fruits and vegetables are not actually necessary for good health. The point was, essentially, that telling people to eat 5-6 servings per day of fruits and vegetables can hopefully drive a beneficial substitution effect. If you tell someone who eats Twinkies, potato chips, and candy bars all day to eat more fruit (and they do), you’ve almost guaranteed an improvement in their health if they eat bananas and apples instead of the aforementioned junk food. That doesn’t mean bananas and apples are “good for you” – it just means they are less “bad for you.” Here’s the kicker, though. We’re led to believe that the reason such folks get leaner and more healthy is because they are eating more fruits or more vegetables or more grains or more [fill-in-the-blank], rather than because they eliminated the most egregious offenders from their diet.

I can’t really overstate this point. I have no intention of engaging in a battle with proponents of plant-based eating or no-saturated-fat diets. I’m reasonably confident that the proponents of these diets are good people who really want to help others and have nothing but the best intentions. But that doesn’t mean we can or should overlook the errors being made in drawing their conclusions. Many people do very well on plant-based (e.g., vegan) diets, for sure. But why are they doing well? That is the single most important question we should be asking ourselves. Why did the people in the China Study who ate more plants do better than those who ate more animals (assuming they did)? Parenthetically, if you actually want the answer to this question, beyond my peripheral address, below, please read Denise Minger’s categorically brilliant analysis of the study.

I know a lot of people who eat this way and, I’ve got to say, these folks do not eat a lot of sugar or a lot of highly refined carbohydrates. In fact, many are so conscientious of their health that they actually have far better carb-habits than most (e.g., which breads they choose, which fruits and vegetables they eat).

While I do plan to write an entire post on this topic of what one can and cannot conclude from an experiment, I do want to at least make the point here: The biggest single problem with nutrition “science” is that cause and effect are rarely linked correctly. Stated another way, it’s one thing to observe an outcome, but it’s quite another to conclude the actual cause of that outcome.

Let me digress for a moment to provide an important example of this phenomenon. One of the most prominent figures in the diet/nutrition space is Dr. Dean Ornish. I don’t know Dr. Ornish personally, and I can only assume that he is a profoundly caring physician who has dedicated his life to helping people live better lives. He is nationally, and internationally, regarded for his efforts.

One of the reasons for his prominence, I believe, is the work he did in the early 1990’s on lifestyle modification and the impact it can have on reversing coronary artery (i.e., heart) disease. In particular, Dr. Ornish was the principle investigator on a trial published in the journal The Lancet in 1990. An abstract of the paper can be found here. But as always, I STRONGLY encourage folks with access (or folks who are willing to purchase it) to read the paper in its entirety. For people who don’t want to read the study completely, or who may not have much experience reading clinical papers, I want to devote some time to digging into this paper. Why? Well, for starters, reading abstracts, hearing CNN headlines, or reading about studies in the NY Times doesn’t actually give you enough information to really understand if the results are applicable to you. Beyond this reason, and let me be uncharacteristically blunt, just because a study is published in a medical journal it does not imply that is worth the paper it is printed on. My mentor at the NIH, Dr. Steve Rosenberg, once told me that a great number of published studies are never again cited (I forget the exact number, but it was staggering, over 50%). Translation: whatever they published was of such little value that no one ever made reference to it again.

I am, to be clear, not implying this is the case for this trial, but I want you to understand why it’s important to read papers fully.

This trial, The Lifestyle Heart Trial, prospectively randomized a group of not-so-healthy patients into two treatment groups: the control group and the experimental group (or what we’d call the “treatment” or “intervention” group).

The experimental group (22 patients) was asked to adhere to the following changes for one year:

  1. Change their diet to a low-fat vegetarian diet (10% fat, though obviously no animal fat; 15-20% protein; 70-75% complex carbohydrates) with several other restrictions (e.g., no sugar, flour, or refined carbohydrates; limited alcohol; no caffeine; limited salt; limited cholesterol intake; no egg yolks)
  2. Smoking cessation
  3. Exercise regimen (minimum of 3 hours per week, at minimum of 30 minutes per session)
  4. Stress management (e.g., meditation, progressive relaxation, breathing modification)
  5. Join social support groups for help with adherence (twice weekly)

The control group (19 patients), obviously, remained under “usual-care” (i.e., no change in lifestyle).

One aspect of this trial that made the results particularly interesting was the use of angiography to actually measure and document the coronary artery lesions (i.e., blockages in the coronary arteries) in the patients before and after the lifestyle interventions. The study was not powered to measure “hard” outcomes (e.g., heart attacks, strokes, cancer, death), so the use of blood markers, physical parameters, and angiography were the best proxies for a reduction in disease risk. In other words, there were not enough subjects in the study to determine a difference in these “hard” outcomes, so we can’t make a conclusion about such events, only the changes in “soft” outcomes. I’m not discounting soft outcomes, only pointing out the distinction for folks not familiar with them.

So what happened after a year of intervention versus no intervention?

First off, and perhaps most importantly from the standpoint of drawing conclusions, compliance was reported to be excellent and the differences between the groups were statistically significant on every metric, except total average caloric intake. In other words, for every intended difference between the groups a difference existed, except that on average they ate the same number of calories (though obviously from very different sources), which was not intended to be different as both groups were permitted to eat ad libitum – meaning as much as they wanted.

Who was “healthier” at the end of a year? The table below shows the changes in both groups. If you want a quick primer on p-values, this is as good a time as any to get one. These tables (i.e., results tables) are a bit cumbersome if you’re not used to looking at them, so let me walk you through one row in detail. Let’s look at HDL cholesterol concentration. In the experimental group, HDL-C fell slightly from 1.00 +/- 0.26 mM (39 +/- 10 mg/dl for Yankees like me) to 0.97 +/- 0.40 mM (38 +/- 15 mg/dl), while it slightly fell from 1.35 +/- 0.52 mM (52 +/- 20 mg/dl) to 1.31 +/- 0.38 mM (51 +/- 15 mg/dl) for the control (i.e., no-intervention) group. It’s hard to tell if this change was statistically significant by inspection, so you glance at the p-value which tells you it was not. (To be exact, the p-value of 0.8316 tells you there is an 83% chance that this difference was random – as a general rule we don’t consider a difference to be statistically significant — meaning we’re going to assume it wasn’t just a chance fluctuation, the roll of the dice — until the p-value is below 0.05, and ideally below 0.01).

Take a moment to look over the rest of the table (or just skip reading it since I’m going to keep talking about it anyway).


Ornish Lancet paper

What else was not significantly changed?

  • Triglyceride level
  • Apoprotein A-1 (not surprising, I guess, since HDL particles carry the bulk of apo A1)
  • Blood pressure, both systolic (“top number”) and diastolic (“bottom number”)

What was significantly changed?

  • Total cholesterol concentration (down in both groups, but significantly more in the experimental group
  • LDL cholesterol concentration (same as above)
  • Apoprotein B (again, to be expected given that LDL particles carry apo B)
  • Body weight (this was, as you can see from both visual inspection and the p-value, the most significant change between the two groups)
  • Though not shown in this table, the experimental group also reported less chest pain severity (though chest pain frequency and duration were not statistically different).

What about the angiographic differences? That is, how did the actual measured lesions in the subjects’ coronary arteries change? 

Seven patients were excluded from this analysis: 1 patient in the control group (patient underwent an emergency angiogram in another hospital, but lesion sizes were not measured); and 6 patients in the experimental group (1 died while exercising in an “unsupervised gym,” 1 could not be tested at follow-up due to a large unpaid hospital bill, 1 patient dropped out, 1 patient’s pre-intervention angiogram was lost, and 2 patients did not have adequate overlay of pre- and post-images).   To justify the findings of this trial we need to believe that the exclusion of these seven patients did not alter the conclusions, but we’ll never know.  This disproportionate exclusion of 6 patients from the treatment group and only 1 patient in the control group, for (perhaps) the most interesting outcome, is (perhaps) the most significant methodological flaw of this trial.

Excluding these seven patients, the experimental group experienced an overall reduction in coronary artery stenosis (blockage) from a mean of 40% to 37.8%, while the control group experienced a progression in coronary artery stenosis from a mean of 42.7% to 46.1%, which was statistically significant.  This trend also held for larger lesions (i.e., those starting out over 50%).  Most importantly, in my mind, within the experimental group there was a strong correlation between adherence score and lesion regression.  Translation: The more rigorously a patient was compliant with the lifestyle changes, the greater was the regression of their coronary artery lesions.  This correlation is quite suggestive that the lifestyle change was responsible for the regression of coronary lesions.

I know what you’re thinking…Is there a point embedded somewhere in here?  Yes.

Here is my point: This was a well-done trial from the standpoint of testing what it set out to test.  It set out to test if a comprehensive lifestyle change could reduce markers of coronary artery (heart) disease, which it did. But that’s it.  It did not tell us if a comprehensive lifestyle change reduced actual heart attacks, which it very well might have if there were hundreds of patients in the study.  It is equally important to understand what we cannot conclude from this study.  We cannot conclude which element of the lifestyle intervention led to the reduction in markers of heart disease.  We know that in aggregate the lifestyle changes made a positive difference, but which ones actually caused the change and which were bystanders remains unknown.

Let’s take a leap of faith and hypothesize that the dietary intervention (rather than, say, the social support) had the greatest impact on the measured parameters in the subjects.  It’s certainly the most likely factor in my mind.  But what, exactly, can I conclude? Can I conclude that a low-fat vegetarian diet is the “best” diet for reducing the risk of heart disease?  Nope.  I can only conclude that a low-fat vegetarian diet is better than the average American diet consumed by the control group (if you are willing to stipulate that the dietary intervention was the most significant driver of outcome).  Why?  Because that’s what was tested.  Unfortunately, this study (and hundreds like it) can shed no light on which specific aspect of the diet in the experimental group provided the advantage.  Was it the reduction in fat intake?  The reduction in animal protein?  The reduction in sugar?  The reduction in simple, highly refined carbohydrates? Unfortunately, we do not know.

SLIGHT DIGRESSION: Tragically, all of U.S. nutritional guidance and follow-from-it policies, recommendations, and food-based infrastructure were derived from this type of science. Maybe their conclusions are correct.  Is fat bad for us?  Are complex carbs the best thing we can eat?  Though theoretically possible, there is no scientific evidence telling us this.  In fact, there is ample evidence actually suggesting the opposite is true.  Hence, this is why – exactly why – we are founding the Nutrition Science Initiative (NuSI) with a group of scientists who all agree that we need to actually test these hypotheses in the most rigorous manner possible, and only then make dietary recommendations.

How bad is it that nutritional recommendations are based on weak science?

Consider the following hyperbolic example: Imagine a clinical trial of patients with colon cancer.  One group gets randomized to no treatment (we’ll call them the “control group”). The other group gets randomized to a cocktail of 14 different chemotherapy drugs, plus radiation, plus surgery, plus hypnosis treatments, plus daily massages, plus daily ice cream sandwiches, plus daily visits from kittens (we’ll call them the “treatment group”).  A year later the treatment group has outlived the control group.  Great news, to be sure.  The treatment worked!  Here’s the problem…we “conclude” it was the 7th and 9th drugs in the group of 14 drugs, plus the kittens that caused the treatment effect and we enact recommendations based on that.  Are we right?  Sure, it’s possible, but actually it’s quite unlikely.  The only way to know for certain if a treatment works is to isolate it from all other variables and test it (in a randomized prospective fashion, of course).   Do the kind of science we were taught to do in 8th grade.

So what do I think happened in Dr. Ornish’s study?  I think the reduction in sugar and simple carbohydrates played the largest single role in the improvements experienced by the experimental group, but I can’t prove it from this study any more than one can prove a low-fat vegetarian diet is the “best” diet.  We can only conclude that it’s better than eating Twinkies and potato chips which, admittedly, is a good thing to know.

Ok, back to the Consumer Reports “best diet” list I started this discussion around.  Another point you’ll note in this table (up at the very top) is the overall amount of caloric restriction in each diet – an average of about 1,500 calories per day.  The caveat here is that these numbers are self-reported, so everything needs to be taken with more than the proverbial grain of salt.  I know what you’re thinking, “Hey, but you said calories don’t matter – why should it matter how many calories these folks are eating?”  Remember, you can always “force” weight loss by creating energy imbalance.  What I mean by that is you can force an energy imbalance if folks are willing to suffer (e.g., work really hard and/or starve).  The reality TV show, The Biggest Loser, is a great example of this.  Participants on the show are basically starved (under 1,000 calories per day) relative to their expenditure (6 hours per day of exercise at a cost of possibly as much as 4,000 calories per day).  The question is, or at least should be, does this form of “dieting” result in long-term, sustainable weight loss?  The overwhelming evidence is that calorie restriction (i.e., reducing calories significantly below active or deliberate caloric expenditure) results in transient weight loss, not sustained weight loss.  Why?  There are a few reasons, but I think the biggest two are:

  1. People don’t like to be hungry, and if they are reducing their caloric intake by reducing fat intake, they seldom find themselves satiated.
  2. Semi-starvation reduces basal metabolic rate, so your body actually adjusts to the “new” norm and slows down its rate of mobilizing internal fat stores.

Furthermore, most people can’t do six hours of heavy exercise a day (not to mention the world is full of people who do six hours of physical labor a day and are obese; I was fat doing 4 hours of exercise per day).  The real tragedy of this is that when folks restrict calories and then resume, when they can’t tolerate the discomfort of relative starvation anymore, they usually end up gaining back all, if not more, of the weight they lost in the first place.

Not to beat a dead horse, but I’d be remiss if I didn’t make this point one more time: When someone reduces caloric intake to 1,500 calories per day – even on a “balanced” diet – they are considerably reducing carbohydrate intake in aggregate and almost always disproportionately with respect to the worst offending carbs (e.g., sugars, simple refined carbs).

Ultimately, the question we’re driving at is, why do these diets work? I argue that each of these diets does some good, especially with respect to eliminating the worst offending agents along the insulin-fat-metabolic derangement axes.   The problem, unfortunately, is that the scientific community is completely confused as to why they work.  Most people think the primary reason these diets work is that they reduce fat intake and total calories.

I argue that reduction of fat intake has nothing to do with it and that the reduction of total calories has a transient effect. And, the majority of the benefit folks receive comes from the reduction of sugars and highly refined carbohydrates. But now I’m repeating myself, aren’t I?


Photo by Markus Spiske on Unsplash

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  1. A little late here, but I just wanted to comment that I’ve lost weight on WW a few times. I lost 45 pounds on WW, but I was hungry and fighting the cravings all the time. Even more disheartening was that my high blood pressure, high triglycerides (over 200) and daily fight with GERD did not improve on WW.

    I went low carb a little over a year ago. I’ve lost 60 pounds, and am much more satisfied than on WW. The best news is that my dietary changes quickly led to normal blood pressure, low triglycerides (50) and no more GERD! While the weight loss is very important to me, the health marker are at least equally imprortant. And, they weren’t improving on a low fat, kcal controlled diet like WW. They did improve on a low carb, high fat diet.

  2. This is such an excellent post as it relates to the need for folks to understand research methodology, which actually yields pretty well to common sense in the hands of someone who knows how to communicate it like yourself (and hopefully other workers in the field like me). Please continue to provide this important instruction in analyzing study methods. Ornish’s work came out just as I was leaving grad school into my first job doing clinical supervision of ketogenic diets in a hospital obesity clinic. His work was all the rage, but it didn’t jibe with what I was seeing, and I really felt the loss of those study participants, along with the “kittens” study design was severely problematic. But it was hard to argue with those CAT scans, they were dramatic and everybody drank the kool-aid. But there was a documentary film made sometime around then about the study participants, and the impression that remains in my memory about it was their fatigue and in some cases, depression.

    What surprised me about the diet comparisons is how much closer to The Zone in percent macronutrients WW has become over the years.

    Don’t even get me started about Biggest Loser…….

  3. I apologize if this was asked but regarding the table at the beginning, how are you arriving at the carb count? For example, how are you getting the carb grams- ie ww 203?
    What do the other figures represent? Fat 24 Carbs 56, protein 20. Calculating fat at 9 Cal per gram and carbs, protein at 4, total Cal total 520?

  4. Currently Consumer Reports is putting a much more measured view of diets on their website. This page is available without a subscription. Although they are still reporting based on popularity, they are finally reporting some of the things we low carb types have known for years:


    An extract:
    “It’s OK to go low-carb

    The 2010 edition of the U.S. Dietary Guidelines for Americans, which we’ve used as the basis for the diets’ nutrition Ratings (available to subscribers), still frowns on eating 10 percent or more of calories from saturated fat from meat and dairy products and more than 35 percent from fats overall. So the Atkins diet, which is 64 percent fat calories overall and 18 percent saturated fat, ends up with only a Fair nutrition score.

    But there’s more to the story. Evidence is accumulating that refined carbohydrates promote weight gain and type 2 diabetes through their effects on blood sugar and insulin. “If you have insulin resistance, your insulin may go up to 10 or 20 times normal in order to control your blood sugar after you eat sugar or carbs,” says Eric C. Westman, M.D., an associate professor of medicine at Duke University who co-wrote the newest version of the Atkins diet. “But the insulin also tells your body to make and store fat. When you restrict carbs, your insulin goes down and you can burn your body fat, so you eat fewer calories and aren’t as hungry.”

    Isn’t it dangerous to eat so much fat? That’s still a subject of vigorous scientific debate, but it’s clear that fat is not the all-round villain we’ve been taught it is. Several epidemiology studies have found that saturated fat doesn’t seem to increase people’s risk of cardiovascular disease or stroke. Other studies suggest that you might be even better off if you replace saturated fat with unsaturated fat instead of with certain carbs, the ones that turn to blood sugar quickly after you eat them, such as white bread and potatoes.

    A nutrition researcher, Frank B. Hu, M.D., of the Harvard School of Public Health, recently wrote that he believes “refined carbohydrates are likely to cause even greater metabolic damage than saturated fat in a predominantly sedentary and overweight population.”

    Moreover, clinical studies have found that an Atkins or Atkins-like diet not only doesn’t increase heart-disease risk factors but also actually reduces them as much as or more than low-fat, higher-carb diets that produce equivalent weight loss. ”

    It’s finally starting to penetrate! CR, for good or bad has a lot of credibility, mostly due to what was stated above, that they don’t EVER accept any money from corporations.

  5. I’ve been eating low carb for 4 1/2 months after a 40 year run on hi carb of mostly whole grains and very low saturated fats. My chloesterol has shot up from 160’s to 250 (Friedewald) but HDL rose to 71, Trig’s down to 27 and a VAP panel has my LDL in the lowest risk category for CVD. So my ratios are all excellent.

    My GP is horrified and thinks I’m a candidate for statins if I don’t bring my LDL’s down. With the elimination of grains and sugar, I have never felt better and returning to that diet is simply not an option for me.

    My question , Is there some science based upper limit of LDL, or TC, beyond which my heart will hit the wall? It seems that as long as my TC/HDL, Trig/HDL, LDL/HDL ratios are all excellent, blood lipids are not collecting on arterial walls or filling up my ventricles, and are just harmlessly going for a ride in my vascular system. My wife’s (same LC diet) TC is 309, with even better ratios than mine.

    Finding this site has been a godsend.


  6. I was once a weight watchers guy and lost around 20-25lbs but that was 15 years ago when I was in my twenties. I have more recently tried WW again and followed it to a T and found that it doesn’t work for me anymore and I’m wondering if its because of years of high carb diets making it harder to lose. I have since dec 2012 been following a paleo/primal diet with no grains or sugar (40-60g of carbs a day) and notice I am never hungry and even though I have not lost an ounce yet, I do see how the constant influx of carbs can really mess up your metabolic state. I’m sure it just takes time of healing on a low carb diet to fix years of the grain/sugar diet to start to see the affects. Love the Website Peter


  7. at 43yo and my waist being 41inches , there certainly has to be some improvements so this seems to be the way to go . WW obviously not. at least for me

  8. Peter, have you heard of the Shangri-La Diet, by Seth Roberts? There’s a few variations of it, but the original idea is that you drink extra-light flavorless olive oil at least one hour away from eating or drinking anything else (except water) – this is to keep the olive oil “unassociated” with flavor calories. Other than doing the oil as directed, you can eat or drink anything. But you don’t feel like eating or drinking anything! Seriously, I had to remind myself to eat and then only wanted to eat healthy stuff. The first time I did the diet, 22 lbs melt off effortlessly and quickly – post pregnancy weight. This was after months and months of calorie counting and exercising. But the second time and third time I tried the diet, the appetite suppression part of it just did not work so I gave up. I feel like my brain figured out the tricks I was trying to play on it. I’d love to hear your thought about this diet, if you’ve ever looked at it. To me, it was Shangri-La, but only worked once. Now after reading this article and all the comments, I’m tempted to try again (since it’s low-carb w/ketosis but WITH massive appetite suppression). I think Seth Roberts is on to something big, but the explanation of why it works isn’t quite right. (sorry for the ramble!)

  9. My anecdotal two cents:

    My 40 lb. weight loss has been maintained for 2.5 years.

    I lost my weight and have maintained the loss by first and foremost counting calories, strictly. I count what I burn in the gym, and count every morsel I eat, and keep meticulous records. I also factor in my baseline level of daily physical activity.

    I’ve noticed that it is easier to maintain my program if I eat big piles of low-calorie vegetables and lean meat.

    My working assumption is that when eating simple sugars and white stuff, like flour and sugar, it is quickly packed away into fat, like a miser quickly depositing money into a bank account, who then says, “OK, I socked that away in the bank account as fat for future use — so how about some some ‘spending money’ to get through the day?” (i.e., I become hungry for more food).

    Whether or not, and to what extent, these working assumptions are true scientifically, I cannot say for sure. All I know is that this “model” works for me. I

    By eating slow-burning stuff such as lean meat and veggies, my body seems to have more “spending money” longer, presumably from not “banking” the calories as fat.

    Placebo effect? Who knows?

    Regardless of what I eat however, as far as I am concerned, the “business end” of my diet is regulating net caloric intake. That is far and away the number one thing I monitor. Having done that, I can then choose which calories will make it harder or easier for me to stick to my diet. (As mentioned, lean meat and lo-cal veggies make it easier to stick to the diet.) However, I never presume that eating protein and veggies will somehow entitle me to eat more calories. For my money, never ever take your eye off the ball of calories.

    One more very important thing, in my view: Do not underestimate the significance of gentle physical activity all day long. In my job, there are days where I am on my feet all day, reaching up into cupboards, and doing gentle lifting of objects. I estimate this burns at least 75-100 calories an hour. In an 8-hour day, that’s 600-800 calories. That’s a lot! It doesn’t feel like I worked out, but I truly did work out — just slowly. On the other hand, there are days where I sit all day long, and I factor that into my net caloric intake calculation.

    I think many overrate the significance of eating lean protein and lo-cal veggies, thinking that calories are not that big of deal if that menu is followed. For my money, however, calories are always and forever the biggest deal, and should never be given a backseat when dieting. Calories are the ultimate coin of the realm. Some calories make it easier to diet, and some make it harder by making you more hungry, but the bottom line, always, is caloric intake.

    One last thing: I have noticed that some of the aerobic machines at the gym are too generous on their digital readouts of calories burned. I correct for this noting which machines are too lenient. I don’t do real vigorous aerobic workouts, so if a machine is saying I am burning more than 500-600 calories an hour, I discount that number. My favorite machine I discount by 25%. If it says I burned 400 calories, I assume I burned 300 calories.

    My anecdotal two cents, humbly submitted.

    Thank you for your great work, Dr. Blogmaster :0)

  10. One of the main problems with measuring “success” on any diet (I’m an ardent WW proponent) is the fact that unless someone starts tracking the post-diet lifestyle for at least 5 years, success must be deemed temporary. People who like to overeat and/or are insulin-sensitive, wheat-sensitive, etc etc, will resume their previous overeating lifestyle. The big trick of course is to stay ever-vigilant and of course, to pick up exercise somewhere along the way. Luckily I love to dance & do dance fitness & other exercise several times a week. However, the scale has to become my friend if I am going to work with it, for the rest of my life. I won’t tell you how many times I have tried unsuccessfully to learn this lesson. Luckily this time I am 4 years “sober” with a 30-lb. weight loss.

    At the beginning of any weight loss journey, the grossly obese don’t care exactly what is happening to their body. They are so thrilled with the LIFE changes happening all around them that all they care about is that it works.
    From my own many years of experience, WW is the easiest program to stay on long term. Yes, carbs are “counted for more points” now so they are discouraged. And yes, some amount of education takes place about generic healthy eating. And yes, fruits & vegetables are strongly encouraged. Like you said above, they are replacing at least some of the junk food. Isn’t that a good thing, at least at first?

    While I am not a WW leader or groupie I do believe that it would be difficult to get too scientific about what is happening in the average WW meeting. It would go over many heads & then they might not attend the meetings. Furthermore as you have so aptly pointed out the science of weight loss is so so complex and personal. I, myself for example, have hypothyroidism & high cholesterol, even with maintenance of a ‘normal’ weight & ongoing exercise for the 4 years. I’m sure there are several other categories of biochemical body types that would need to be studied on a long term basis (post-weight loss), including testing all the possible sensitivities you’ve mentioned.

    A friend recently told me that I need not ever eat anything that starts with a ‘w’ and ends with a ‘t’, again (because of my high cholesterol, 274). I’m at the first-step stage, admitting I am powerless over certain types of foods. I think analyzing some of the various sensitivities would be a good next step.

  11. Hi Peter:

    Well, I’m very impressed with all the statistical analyses you’ve done about what diets work, why people lose weight, why they don’t, what nutrients work best, who lost what type of weight in clinical trials, studies of how much weight was lost etc. etc. etc. But is all this really necessary? Seriously, I would have an easier time trying to figure Einstein’s Theory of Relativity than it was trying to follow your article. Please don’t get me wrong, I’m sure it was full of factual information and great advice, but again, is it really necessary?

    People today are getting fatter and fatter, can’t lose weight or yoyo diet because they can’t control their impulses when eating. This is in part fueled by the food industry using clever marketing tactics to entice people to constantly eat bad, unhealthy food and too much of it; and society has lost control of themselves as a result. The diet industry then comes along to take advantage of this and says “okay, such and such a diet is good for you because you need to cut out (pick one – fats, carbs, sugars, salts, saturated fats, hydrogenated fats, refined starches etc. etc. etc.). Then there’s all these studies done about the best way for the body to metabolized calories, but they all seem to ignore good old fashioned common sense. Why do we keep referring to “new science” or “old science” when all it takes is for people to eat sensibly, not consume as many calories and exercise? It’s worked in the past. The dieting advice from yesteryear with our parents & grandparents would be to “push the goddamn chair away from the table”. There was no Weight Watchers, Jenny Craig, Atkins, South Beach, Grapefruit diets and so on. People ate all types of foods but ate sensibly. This includes having a controlled portion of meat, chicken, fish etc. with a side starch and plenty of vegetables. Yes, you can have a daily sweet snack like ice cream, cookies, cake but don’t pig out. Also eat plenty of fruits & veggies as snacks in lieu of extra breads, cakes, cookies or anything else with high refined wheat content. Then get a good deal of exercise. It’s that simple.

    • I lost twenty pounds without exercising, just by dramatically reducing the carbs in my diet (except for binge day, when I overload, to keep the metabolism up.) Exercise is overweighted. Exercise just causes you to burn calories, make you hungry, and if you eat more calories that spike your blood sugar and invoke the insulin response, you’ll just get fatter.

  12. I read the article, and didn’t read all the comments. Sorry if I’m repeating something someone already said. I want to point out one more confounding factor for the study discussed: the people who changed their lifestyle KNEW they were in the experimental group. If you take a group of people, split them in two, tell half that they are the control group, and the other half that they are the experimental group, it doesn’t matter what you are testing or how you then test it, the experimental group will do better at whatever you are testing for. Even if it’s autonomic. Even if you don’t tell them what you’re testing for. Even if you don’t tell them who is the control and who is the experimental group (because YOU know which is which — the Clever Hans effect — double blind studies FTW).

    You are definitely right — this kind of thing is *tough* to study, and I feel sorry for everyone who has tried and failed in predictable ways.

  13. I appreciate your clear presentation of the information. I have to say, as someone who has struggled with weight loss (-40 would be good for me) I have lived in the realm of shifting from one place of thinking to another. I’ve tried Weight Watchers, shifted to ‘green juices’ for 3 meals a day, shifted to a vegetarian diet, shifted to a carb-free diet, and then the cycle just continues. The bureaucratic LIES that continue to be FORCED upon the American public is just outrageous. I no longer believe almost ANYTHING I read about health, wellness, and weight loss – as I never know which company has paid to have their beliefs included in the report.

    I would love more information – or sites – that accurately report what nutrition is best for weight loss and your body in general…. For example – I’m still confused if it’s better to add a bit of sugar or splenda to my coffee???

  14. Six people in the experimental group had to be dropped from the data. One died while exercising – unsupervised. I not sure of the significance of the unsupervised comment. Did the instruction tell them to exercise only under supervision. If this experimental group person has been supervised would he have lived? We will never know.

    Instruction: Exercise regimen (minimum of 3 hours per week, at minimum of 30 minutes per session.
    If this was the only instruction given then this treatment was, in my opinion poorly defined. I could exercise for 3 hours at one time or 2 hours a day six days a week. The fact that six subjects had to be excluded make me suspicious of the positive results.

    My psychology experiment in college was “The Affect of Transcendental Meditation on Perception Ability and Reaction Time while Under Varying Condition of Stress”. Very small group of subjects. Between secession the subjects were asked to meditate or sit quietly, My sit quietly was a problem. One of the subjects learned after the test that she was pregnant. By excluding her score I was a able to get P value of .05. I later learned that one of the grad students in the study instead of sitting quietly smoked a joint. The lesson – it is hard to control variables even in small groups.

    My first reaction in reading your post was the fact that 6 subjects in the experimental group were excluded compared to 1 in the control group. Was this a random exclusion event – could the exclusion rate between groups have been tested for a P value?


  15. Different diets work for different people. I’ve tried Atkins a few times, and just can’t make it past the first stage of having 20 grams of carb a day. I have neverending headaches, and the only energy I have is from diet Mountain Dew, so little it’s hard to sit and concentrate at work, a sedentary job. Weight Watchers, though, works very well long term. It’s not so much low carb, as it is just simplified portion control. Nothing is off limits, it’s just how much carb, fat, protein, fiber, etc is limited. I can see why, for some people, it wouldn’t work so well, if they’re short and are older (slower metabolism), like my mom, you get the minimum 26 points. I, on the other hand, at 5’11” and 18, get 56 points, which is really more than I usually eat anyway. Just drinking diet drinks is pretty much all I have to do.

  16. I’m really not a big fan of people saying “there’s no evidence of” this and that.
    I hear it all the time from vegans and low fat dieters and the like, with regards to saturated fats, high fat diets or ketogenic diets being healthy. I feel the same way when someone says there is no evidence the opposite is true (no evidence of saturated fats, high fat diets and keto diets being unhealthy). I respect you, Peter, almost more than anyone in the world (in fact, I’ve added you to my “list of people to meet before death”, which only holds 4 names), but if there really is no evidence that fat is bad, then why do we have seemingly extremely intelligent human beings like micheal gregor, john mcdougall, dean ornish and neal barnard saying otherwise?
    I don’t believe it’s possible for them all to be tricked by the corruptness of nutrition science. I understand there’s been a lot of mistakes (mostly ancel keys) with research on nutrition and the literature and what people class as “evidence”, but surely those names and other similar folks who see low fat diets as healthy aren’t automatically stupid, gullible or tricked?

    To put all this into one sentence: I truly believe if there was no evidence for either side (LCHF = good, or veganism = good, and when I say side, I do know it’s not just two teams, there’s plenty of different diets), then why would there be any debate between these highly educated people?

  17. I’m not seeing much research being published that includes women. Is it there, and I’m just not seeing it? Or is the literature omitting women from studies – and if so, why? We at least appear to be under-represented, which is peculiar since 90% of the obese humans I know (including me) are women, and women are socially more likely to set the “food tone” for the next generation.

  18. There is always something new to learn, and I appreciate Dr. Attia for his approach as well as his knowledge. I lost 100 lbs. on Weight Watchers, and have kept 90 lbs. of it off for over a decade. Early in the process, I realized the goal was a heightened understanding of your patterns, rather than the diet itself. I continue to count points, and have learned a great deal about my own habits as well as the lack of science in nutrition. Nevertheless, I’ve watched Weight Watchers do exactly what medicine has done in my life time as an MD-test new hypotheses and hope an understanding of science helps us make informed decisions.

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