![]() ![]() Metabolic adaptation, therefore, is the reduction in basal metabolic rate seen in individuals who are losing or who have lost weight, that is not explained by their lost tissue – and make no mistake tissue will be lost. ![]() In short, 35% of the reduction in BMR (which represented roughly a 15% reduction overall) was not explained by lost tissue, this was adaptation. Not only that, but these individuals will be lethargic thus move less, and so their TDEE will of course go down somewhat.ģ5% of the reduction to basal metabolic rate, however, (equal to around 180kcal per day) was not associated with reductions in lean body mass or fat mass, and because we’re looking at BMR that means that activity isn’t relevant here either (1). This makes immediate sense, a 60kg person requires fewer calories per day than a 100kg person assuming similar activity levels, and so the fact that their calorie needs reduced after 25% weight loss should come as no surprise. When you lose weight you lose tissue, and you become lighter so easier to move around – both of these factors result in a reduction in energy requirements. As would be expected the total daily energy expenditure (TDEE) of each man was reduced, but this is where the first important detail comes in. The goal was to reduce their bodyweight by 25%, so slightly over 1% per week.ĭuring and after this process a lot of data were collected, helping researchers in a number of fields including that of eating disorders to the modern day, but for our purposes we need to look at their metabolic rates. This was maintained for 24 weeks, during which time each man was required to walk 35km per week and complete work tasks. The design was relatively simple, 36 conscientious objectors to WWII had their calorie intake reduced from around 3200kcal to around 1560kcal using foods likely to be available during the time (the diet was pretty low in protein). Note that while these data are very old they are still considered some of the most reliable and useful in the field of starvation due to the depth of analysis and excellent study design. The first thing I need to do, however, is to outline exactly what adaptation is, and for that we can look back to the now famous Minnesota Starvation Trial conducted by Ancel Keys and colleagues between 19. Regardless of their interpretation, metabolic adaptation is discussed as some kind of absolute inevitability for everyone who starts to diet by anyone who mentions it regularly, and so one of my intentions with this article is to explore what currently IS known about adaptation, it’s magnitude, and the chances that it would affect you personally or your clients. ![]() Part of the reason for the confusion is that, actually, the idea of metabolic adaptation to weight loss isn’t as clear-cut and well understood in the scientific community as most seem to think it is. What this means is that we have two separate problems: first, when the topic of adaptation comes up people talk past each other because they interpret the term completely differently and so talk about different things, and secondly, at least some of these people are probably interpreting it incorrectly. Adaptation makes dieting impossible and so dieting doesn’t work, therefore you shouldn’t try.If you diet you’ll go into starvation mode and gain fat.Adaptation always happen when you cut calories, so calorie reductions don’t work, so do keto or something.The more times you diet, rebound, and diet again, the worse your adaptation gets.To reverse the adaptation, increase calories slowly.The faster the weight loss approach, the greater the adaptation is going to be.This is often used as an argument for keeping kcal high when dieting after all, if you start on 1000kcal, where do you go when your body adapts to that? As you diet, your body will adapt to the number of calories you are eating and so you have to reduce calories further as you go. ![]() Ideas commonly shared include but are not limited to: Metabolic adaptation to weight loss – the phenomenon of reduced energy expenditure during and after a period of calorie restriction, is probably one of the most misunderstood topics related to nutrition and body composition. ![]()
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