Body Composition & DEXA

Many of us use body weight or BMI (body mass index) for a quick approximation of our health status. Yet the utility of these metrics is limited because they provide little information about a far more relevant parameter: body composition – and in particular, body fat and its distribution. Body weight and BMI alone do not discriminate between muscle mass (which we want to maintain or increase to promote longevity) and fat mass (which we generally want to keep relatively low). Thus, when we set a goal to “lose weight,” our real aim ought to be losing fat.

Losing fat mass isn’t necessarily easy, but unfortunately, that struggle pales in comparison to the challenge of keeping it off. This is caused in large part by a hormone called leptin, which is secreted by fat cells and plays a critical role in numerous endocrine pathways and functions, including the regulation of energy homeostasis. Leptin is secreted at levels proportional to body fat and acts as a “satiety hormone” in the brain, causing a reduction in food intake. However, as leptin signaling decreases – due to fat loss or to key neurons becoming leptin-resistant – the brain interprets this as a sign of starvation, and drives increased appetite and reduced energy expenditure to counteract the loss.

The content selections below provide more information on the accumulation and measurement of body fat, different types of fat and their relative impacts on health, and the effects of leptin on appetite and metabolism.

Risks

QPS

Peter’s key takeaways on bone health, calorie restriction, gene editing and more

Ep. #325

Nutrition

Guest Episode

Metabolism, energy balance, and aging: How diet, calorie restriction, and macronutrients influence longevity and metabolic health

Ep. #324 with Eric Ravussin, Ph.D.

Medications & supplements

AMA

New insights on GLP-1 agonists (Ozempic, Wegovy, Mounjaro)

Ep. #320 (AMA #64)

Nutrition

Guest Episode

Rethinking nutrition science: the evolving landscape of obesity treatment, GLP-1 agonists, protein, and the need for higher research standards

Ep. #314 with David Allison, Ph.D.

Nutrition

AMA

Protein’s impact on appetite and weight management, and uric acid's link to disease and how to manage levels

Ep. #313 (AMA #62)

Nutrition

AMA

Preventing cognitive decline, nutrition myths, lowering blood glucose, apoB, and blood pressure, and more

Ep. #306 (AMA #60)

Nutrition

Premium Article

Body composition: impact on disease risk and how to assess and improve it

Nutrition

Guest Episode

Optimizing muscle protein synthesis: the crucial impact of protein quality and quantity, and the key role of resistance training

Ep. #299 with Luc van Loon, Ph.D.

Nutrition

Free Article

Does time-restricted eating increase the risk of cardiovascular death?

Nutrition

Premium Article

Optimizing protein quantity, distribution, and quality

Nutrition

Free Article

New insights on maximizing protein utilization for muscle protein synthesis

Nutrition

Premium Article

Sugar substitutes: deep dive into the pros, cons, available options, and impact on metabolic health

Nutrition

Free Article

How does aging increase risk of dehydration?

Nutrition

Premium Article

The cases for and against dietary protein for healthy aging

Nutrition

Free Article

Does carbohydrate load impact the balance between fat storage and oxidation?

Medications & supplements

Free Article

Is a recent clinical trial enough to support the use of semaglutide in treating adolescent obesity?

Nutrition

AMA

Peter’s historical changes in body composition with his evolving dietary, fasting, and training protocols

Ep. #242 (AMA #44)

Nutrition

Free Article

To reduce appetite, skip late-night snacks

Exercise

Guest Episode

Training principles for mass and strength, changing views on nutrition, creatine supplementation, and more

Ep. #235 with Layne Norton, Ph.D.

Exercise

Guest Episode

Improving body composition, female-specific training principles, and overcoming an eating disorder

Ep. #228 with Holly Baxter, APD

Nutrition

AMA

Body composition, protein, time-restricted feeding, fasting, DEXA scans, and more

Ep. #227 (AMA #40)

Nutrition

Guest Episode

Dietary protein: amount needed, ideal timing, quality, and more

Ep. #224 with Don Layman, Ph.D.

Nutrition

Free Article

Different effects of fat- vs. carbohydrate-restriction on neural reward signaling

Nutrition

Guest Episode

The neuroscience of obesity

Ep. #212 with Stephan Guyenet, Ph.D.