The typical scenario goes like this: you have been dieting for a while and you have managed to lose quite a lot of weight at the initial stages of the diet, but now weight loss has come to a halt. After a quick search online, you decide that your body is in starvation mode and that’s the reason you are not losing any weight. But, is your body really in starvation mode and does starvation mode actually exist?
What is starvation mode?
According to Wikipedia, starvation mode is a state that occurs after long periods of abstinence from food or very low calorie intake. It doesn’t happen if you don’t eat for a few hours or even a couple of days. During short periods of abstaining from food, your body will burn mainly fat from its fat stores. It will only burn lean tissue as a fuel, after the body fat gets depleted. This means that as long as you still have excess fat on your body, there is no need to worry about muscle loss, unless you go through a prolonged period of starvation. The notion that the human body will use lean tissue first and leave its fat stores intact is a myth. Have you ever seen a fat anorexic?
Metabolism and starvation mode - What happens in starvation mode?
A large part of what we know about the human body starvation mode and its effect on metabolism comes from Ancel Key’s Minnesota starvation experiments in 1950. The participants of this study were at 50% calorie deficit for a period of 6 months and experienced a 40% decrease in metabolism. However, this happened after the depletion of their body fat stores. So, starvation mode is real, but you are very unlikely to ever experience it in your lifetime.
If you currently have extra body weight, then you are probably not in any "starvation mode" and there is no need to eat more calories, in order to “kick start" your metabolism. You can’t “eat more to lose weight”.
A few facts about human metabolism
Approximately 70-80% of your basal metabolic rate is driven by the energy burned from your vital organs and mainly your brain, heart, liver and kidneys. This means that you are going to burn a certain amount of calories per day, no matter what you do. Food consumption or the lack of it has a very small effect on metabolism.
If you eat very few calories, you may experience a small drop in your metabolic rate, but this reduction is never larger than the deficit itself. For example, let's say you are only eating 800 calories per day and your metabolism normally burns 1800 calories. With a 1000 calorie daily deficit, you should expect to lose about 2 pounds per week. Even if your metabolism does slow down by 10-20 %, you should be able to lose at least 1 pound per week. Weight loss would simply be slower, but it wouldn’t stop completely.
Starving yourself to lose weight is not necessary and can be dangerous, but starvation mode doesn’t explain why you are not losing weight. You should still be losing weight, even if your body was in starvation mode. So, why aren’t you losing weight? It could be water retention or there may be errors in calorie counting. There is another possible reason: you may not have enough fat left on your body to support a rapid fat loss. As your body fat levels go down, fat loss will be much slower. This is actually the time to increase your calorie intake. Most people reduce their calorie intake at the final stages of their diet, which may not be such a good idea. This phenomenon is wonderfully explained by Brad Pilon and John Barban in the Venus Index (for women) and the Adonis Index (for men).