If you’ve ever dieted before, and since you are reading this I am sure you have, you experienced what scientists call adaptive thermogenesis. Also referred to as the starvation response, adaptive thermogenesis is a set of adaptive biochemical and physiological changes that reduce metabolism in response to a decrease in caloric intake or a spike in energy expenditure.
You have noticed, for certain, that it is very easy to lose weight at the inception of a diet or cardio program, but with each passing week and every pound lost, it seems to get harder and harder. Eventually it can even get to the point where you are eating a fraction of the food you started with and doing lots of cardio yet your weight is flat lined. On top of this, you feel lethargic, drained, and depressed. This is part of it as the body feels it is starving and may not have enough energy to function, so it significantly reduced your caloric expenditure in all aspects, in essence, to keep you alive. While that worked great 3000 years ago when your tribe couldn’t get enough food to feed itself and a down-regulation would allow you to survive longer, it has a negative effect today when it comes to losing body fat.
The reason adaptive thermogenesis takes place is due to a predictable caloric deficit (either from increased expenditure or decreased caloric intake, or both). So, with a flat increase in caloric deficit, the body sees exactly what is happening and adjusts accordingly. Not unlike a batter who just saw 6 straight fastballs would be expecting a fastball as the next pitch, and would be ready for it. The best thing a pitcher can do is throw a 65 mile an hour changeup, and the batter is caught off guard. Dieting works the same way. Eat 1500 calories every day for a week, and on the eighth day your body has adjusted itself down to get through the day on 1500 calories. So how can we combat this effect?
Temporarily increase calorie intake – This goes beyond a cheat meal. Cheat meals are more effective to prevent adaptive thermogenesis, but at some point, even cheats stop working. Why? Because cheat meals are a flash in the pan from a metabolism standpoint. They are good for a quick spike, which is often enough, but after they are over, you are right back to the same calorie deficit and the body never had to adjust to a sustained increase in calories. Instead. Try increasing calories (carbs/fats) by 30-40% for a full three days to a week. This will force the body to adapt to the higher sustained intake by increasing metabolism, however won’t be an increase high or prolonged enough to induce any real fat storage.
Back off the training/cardio – This has a very similar effect to the above. A decrease in energy expenditure decreases the caloric deficit and allows the body to reset. If you are doing 1+ hours of cardio per day, maybe stop cardio entirely for 3-7 days, or if you are doing less cardio, back off the cardio some as well as decrease weight training volume and intensity. This serves the dual purpose of allowing your metabolism to reset as well as destressing the system so you can recover fully, which is a further issue on calorie restriction.
Dramatically alter meal timing – This is the dieting equivalent of a changeup. If you eat the bulk of your carbs before training, move them to later in the day. If you eat cars spread out throughout the day, load them to the front of the day for a few days. You may even find that these changes work better with your particular circadian rhythm and you end up stumbling on to some added benefit to perform better.
Nearly every diet fails in one way or another due to adaptive thermogenesis. People are motivated by results, so if someone is continually losing 5lbs per week, they are much more likely to continue on their track then a person who hasn’t lost a pound in three weeks. Consider that the body does not WANT to be super lean, and will fight you on it. Throw it some changeups to keep it off guard and you are much more setup for success.