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One of the things that has always fascinated me—and if I’m being honest, increasingly frustrated me—in the ongoing diet wars is the persistent need to argue that one dietary approach is the perfect diet. A diet that solves every problem, creates no trade-offs, and carries no meaningful downside.
That’s a strange position to take. Not because diets don’t differ. They clearly do. But because if you step back and look at this through even a modestly scientific lens, a more obvious pattern emerges. Most structured diets that impose meaningful constraints tend to produce benefits relative to the baseline diet most people are actually eating.
And that baseline matters.
The standard American diet is not a neutral comparator. On average, it is characterized by excess energy intake, high levels of refined carbohydrates and ultra-processed foods, insufficient protein quality, and poor micronutrient density. When you impose almost any coherent structure on top of that, whether it’s carbohydrate restriction, plant exclusivity, time restriction, or simply greater caloric awareness, you reduce entropy in the system. You remove degrees of freedom that were previously allowing overconsumption and poor food selection.
So it’s not surprising that many diets work.
What is surprising is what happens next. Instead of acknowledging that a given diet improves certain variables while potentially worsening others, proponents often move to defend the diet as universally optimal. The upsides are amplified, and the downsides are dismissed, minimized, or in some cases denied outright.
This is the point where the conversation stops being about nutrition and starts being about ideology.
At a more fundamental level, every diet is an optimization problem under constraints. It prioritizes certain biological outcomes at the expense of others. So the real question is not whether a diet is good or bad. The real question is what is it optimizing for, and what are the trade-offs required to achieve that optimization.
To make that more concrete, it’s useful to look at two ends of the spectrum.
