We’re going to be looking at the idea that if you diet on too low of calories or too low of a caloric intake then your body will enter starvation mode and prevent you from losing any further weight.

Where did this idea come from?

This idea comes from one of two main lines of dieters reasoning.


People hate low-calorie diets, so they’re on the lookout for a theory that justifies eating more food. So people have basically come up with this idea a starvation mode so that they get to eat more food while dieting.


Dieting legitimately encounters stalls or sometimes even spikes in weight, despite being on very low calories but still don’t see the weight loss they’re looking for. So they’ll encounter a weight loss stall or in some cases notice that their weight spikes despite being on low calories. This fits in very nicely as “EVIDENCE” in support of the “STARVATION MODE” theory.

Where did this idea go wrong?

When you look at examples of people WHO ARE ACTUALLY STARVING, they look emaciated with VERY LOW BODYWEIGHTS AND BODYFAT PERCENTAGES.

They don’t ever really seem to counter a point where they start gaining weight or stop losing weight. It seems to be the case that most people who posit starvation mode as a deterrent to weight loss are people who are dieting in the first world without a whole lot of results.

What does the science say?

The first study shows that the researchers took 32 men and put them on a semi-starvation diet meaning they were in a 55% caloric deficit for 24 weeks. Now 55% is a really big deficit just for some context I’ll typically put clients on a 15 to 25 percent caloric deficit for weight loss depending on their goal. So 55 percent is pretty huge and they went from an average of about 3400 calories to about 1,500 calories per day and then follow that same 1,500 calorie diet for 24 weeks straight. At the end of the 24 weeks, the researchers didn’t find that any of the subjects had entered starvation mode and stopped losing weight or stopped losing body fat but they instead found was that all of the subjects lost a ton of weight with the average weight drop in 25% of their starting body weight.

Their metabolisms did slow down by quite a lot throughout the course of the experiment and I think that this is where there is a hint of truth to the sort of starvation mode hypothesis where the body will slow down some of its metabolic processes in response to a very strong caloric deficit. In fact, by the end of the study, the subjects had experienced an average drop in metabolic rate of 40% now of that 40% drop about 25% was just due to a reduction in body weight alone. So there’s less metabolically active tissue requiring fuel requiring energy so all else being equal bigger bodies tend to burn more calories and smaller bodies tend to burn fewer calories but that still only accounts for 25% of the metabolic drop and so the other 15% is due to an adaptive metabolic slowdown. I think this is the true metabolic slowdown seen in this literature I mean it’s made up of a metabolic component known as adaptive thermogenesis. so after we account for losses in body weight we’re really only looking at about a 15% drop in metabolic rate and these subjects got to 5% body fat before seeing even this level of the metabolic slowdown.


NEAT: Any form of activity other than formal exercise like tapping your feet, bobbing your head to the music, etc.

Losing metabolically active body mass the main reason why your fat loss begins to slow down later in the diet is that your levels of meat downregulate. So you may notice you’re a little bit less fidgety or you tend to move around a little bit less and this is in large part subconsciously regulated in the brain and it also happens to be very individual.

One 2014 study, found that need can vary up to 2,000 calories between two individuals at the same body composition, same gender, and age meets also and very large part explains the differences you see amongst individuals in response to the same diet.

A 1999 study, Levine and colleagues gave subjects in excess of 1000 calories per day for eight weeks and at the end of the eight weeks the amount of fat gained varied from just 0.79 pounds all the way up to nine point three pounds that’s more than a tenfold difference among individuals in response to the exact same caloric surplus and offers of this paper it should be a very large chunk of this to individual variation in levels of meat. So the bottom line in terms of practical application is that as someone seeking fat loss you want your levels of meat to be as high as possible.

Dieting MORE SLOWLY helps to PRESERVE NEAT LEVELS better than VERY LOW CALORIECRASH DIETS“. It tends to be associated with greater reductions in need and the more slow steadier approach with more of a moderate caloric deficit.

A 2013 study, a 2013 study titled Weight loss, weight management, and adaptive thermogenesis found that neat downregulates more the faster and harder you diet. If you try to cut very aggressively, your body decreases Neat to decrease your energy expenditure, thus decreasing weight-loss. Other research has shown that slower diet also tends to preserve muscle mass better and lead to a less post-diet rebound.

Why do so many people still experience weight loss or weight gain, when running a low-calorie diet?

  1. Adaptive metabolic slowdown (downregulated neat) is greater with low-calorie diets.
  2. People are really bad at estimating their caloric intake and energy expenditure.
  3. Weight stalls or spikes due to water retention.

In 2006 article, showed that 65 women take a 7-day log of their calories underreported caloric intake by an average of 37 percent. So that would be like saying you ate 1600 calories when in fact you made about 2500 calories and that’s an enormous difference and this is a trend that’s been shown over and over again and the scientific literature and I think it’s worth pointing out that it may not be intentional underreporting. It could be the case that they’re just not getting accurate tracking information from say eating out too frequently or maybe they’re forgetting about things that they ate earlier on in the day and just forgetting to report. The end result is still the same.

If you’re retaining water for one reason or another that mean your menstrual cycle or high levels of stress then that can be masking your true weight loss on the scale or you are in fact losing body fat because of the caloric deficit but the subsequent retention of water is sort of disguising that. Most of these changes are acute meaning that if you are just patient enough with the diet over enough time then you should see that water sort of come out and that usually happens in the form of a swoosh. So you’ll see your body weight suddenly drop three or four pounds despite being installed for a month or in some cases and more.


In conclusion, your low-calorie diet isn’t putting you in starvation mode and there’s no evidence for that all of the scientific literature that we have and I think instead there are three other better explanations for why your weight loss may be stalled despite being on very low calories.

  • The first is that you may be eating more you think research shows that people are really bad at estimating their caloric intake and they very often tend to underreport. In some cases by quite a lot.
  • A second has to do with variables like stress from the lack of sleep, maybe excessively high fiber intake or really any other factor that could be causing water retention.
  • Thirdly, your diet may just be too low in calories and that could be suppressing your levels of meat and reducing your total daily energy expenditure overall.

Despite starvation mode not being a real thing, I still generally don’t usually recommend very low-calorie diets. They tend to cause worse metabolic adaptations, more muscle loss, and sometimes worse post-diets rebounds. For fat loss, you generally want to be somewhere in the 15-25% calorie deficit range or be losing – 0.5-1% of body weight per week.


Scientific References: