I just finished this book and it contains a lot of insights that are highly relevant to /r/loseit, so I thought it'd be nice to share what I learned. Some of this is widsom commonly shared on this sub along the lines of "you can't outrun your fork", but a lot of it is new information to me. To keep this post brief, I'm going to focus purely on the takeaways for those of us trying to lose weight. Read the book to learn the "why" and evolutionary theory, discussion of how the body compensates for exercise in various subsystems, the studies that were done, etc.
- The "shocking" research: Hunter/Gatherer populations alive today like the Hadza do enormous amounts of physical activity per day (5+ hours) but have similar TDEE to sedentary Americans (2500-3000) cals. This is the shocking research mentioned on the cover and challenges the long held "factorial model" that active calories can be added to resting+digestion calories to compute TDEE. Instead Pontzer presents the "constrained energy model", in which active calories are compensated for by reductions in other expenditure, keeping TDEE in a fairly narrow range. As exercise is added, energy expenditure does not increase at anywhere near the same rate.
- TDEE variability: individuals vary greatly from the standard TDEE. Deltas of 200-300 calories are not abnormal, so don't trust the calculators too much.
- Exercise does increase expenditure, but by much less than you'd think. He cites a study where doing 3000 extra calories of activity per week only resulted in a ~220 boost to TDEE, around half of what you'd expect from the factorial model. Another study of women training for a marathon is referenced where their exercise calories were up by at least 360 per day but their TDEE only went up by 120. The author sort of dismisses these increases as trivial and writes as though they're basically 0 throughout the book, but IMO saying that you get 1/3rd-1/2 of your exercise as TDEE increase is nothing to ignore.
- Diets: Keto, low carb, low fat, "mono-food" etc. diets all work equally well as simple calorie restriction. The best diet is the one you can adhere to that puts you in a calorie deficit, and it's not necessary to avoid entire food groups. He recommends focusing on a diet that keeps you satisfied in a calorie deficit, and prioritizing protein, fiber, and limiting processed foods helps with that.
- Rapid weight loss significantly reduces BMR and this effect can last for multiple years! Study of "Biggest Loser" contestants showed much lower than expected BMRs for body composition, and the effect was still observed 6 years later. This effect isn't observed with more gradual weight loss.
- Exercise is still important: He spends an entire chapter on why exercise is still very much worth doing and critically important for humans to survive and prevent all forms of cardiometabolic diseases, reduce inflammation, etc. A modest amount of exercise dramatically reduces risks of dying from many different causes.
- Maintenance: Even though exercise isn't a primary driver of *achieving* weight loss, it does seem to be a primary driver of *maintaining* weight loss. It seems that the hypothalamus-induced energy intake targets (which regulate hunger and satiety) were based on the pre-diet BMR, when people were heavier. To keep the weight off they had to exercise to keep their energy intake in line with expenditure and avoid weight regain.
- Extreme endurance athletes: He talks about the effects of overtraining and the limits pushed by extreme endurance athletes. Tour de France, ultra marathoners, ironman triathlon, etc. In the short to medium term we can consume enormous amounts of energy per day, way above the 2500-3000 kcal norm. But as these activities go on for weeks or months, our bodies begin to shut down other functions and can't possibly compensate enough (i.e. we stop producing estrogen/testosterone, women stop menstruating, immune health is reduced, etc.), A group of runners who ran a race across the US, running a marathon every single day for 140 days, were studied. Their expenditure started at 6200 kcal per day early on and dropped to 4900 kcal by the end as the body began to shut down other functions to compensate. The author plotted all these extreme endurance sports on a curve for the activity level and duration and found it actually fit the sustained expenditure associated with human pregnancy, suggesting that pregnancy represents the upper limit of how much a human body can increase expenditure over time.
TL;DR don't do what I first did and take your sedentary TDEE and then add your exercise calories and assume that's your expenditure. You'll almost certainly drastically overestimate your TDEE that way. This is exactly what MyFitnessPal does by default! Also don't trust TDEE calculators as there's too much individual variance, use your actual calories and weight data to compute your true TDEE (or use an app that does it for you, like MacroFactor). Diet is going to be the primary driver of weight loss, but exercise is vitally important to overall health as well as maintenance of weight loss.
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from loseit - Lose the Fat https://ift.tt/QJ8KSxN
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