Participants of extreme weight loss challenges such as The Biggest Loser often gain back most or all of the weight they lost during the challenge. Some gain even more weight than they lost.
One explanation for this is adaptive thermogenesis. Adaptive thermogenesis is essentially a decrease in heat production during an energy deficit to conserve energy1. In other words, in response to decreased energy intake, the human body decreases energy expenditure.
As both resting and non-resting energy expenditure decrease2, the body may lower activity throughout the day or decrease intensity during cardio sessions without you noticing. You do not have to be at a certain body weight or body composition for this to happen.
To lose weight, calories out must exceed calories in. If adaptive thermogenesis decreases the “calories out,” then it makes sense that the way to combat adaptive thermogenesis is to keep decreasing how much we eat (“calories in”). The other option would be to increase “calories out” by exercising more.
However, there is evidence that many other tools exist for combatting adaptive thermogenesis. Let’s explore the following possible ways: Refeeds, diet breaks, untracked meals, reverse dieting, and eating ad libitum.
One of the many hormonal effects of dieting is a decrease in leptin, the “satiety hormone,” which partially explains why it is so difficult to feel satiated when dieting. A refeed is one or more high-calorie days designed to increase energy expenditure and levels of leptin and insulin3,4.
As carbohydrates are the macronutrients that have been shown to have these effects4,5, carbohydrates should be the main focus of a refeed day. However, certain people may feel better with more or less protein and fat on refeed days.
For example, in females, an increase in leptin can help to combat loss of menstruation which can occur when dieting6. Increasing insulin can help to reduce unwanted side effects of dieting, such as increased muscle protein breakdown and decreased testosterone.
Refeed days increase glycogen stores so that you have fuel – and, hopefully, increased intensity of workouts – in the days following the refeed. When deciding which foods to prioritize on refeed days, keep in mind that carbohydrates will also help to increase glycogen stores, which decline when dieting.
The amount that calories should be increased on a refeed day will depend on many factors, including genetics, age, gender, physical activity level, length and severity of caloric deficit. Many people do well with increasing their carbohydrate intake by 50-100% on refeed days, but those in a long and/or severe caloric deficit may require an even greater increase.
Many dieters like to have refeed days weekly. You can always experiment each week and see what type of carbohydrate and/or caloric increase makes you feel best throughout the rest of the week.
2. Diet Breaks
A diet break is, obviously, a break from one’s diet. The term “diet break” is also used to refer to a specific approach to combatting adaptive thermogenesis. In this case, a “diet break” is not simply a hiatus, but rather a highly structured break in which calories are increased to at least maintenance level.
“Maintenance calories” means the number of calories needed to maintain your current weight. A diet break may last for days or, ideally, weeks to give time for hormones such as leptin and thyroid hormone to return to more normal levels.
Finding your “maintenance calories” can be complicated, as adaptive thermogenesis will require a decrease in calories to maintain your weight. A generic guideline for calculating your maintenance calories is to take your average calories per day and add 500 calories multiplied by the amount of weight have been losing per week.
For example, if you have been consuming 2000 calories per day and have lost 4 lbs over the last month, add 1 lb x 500 = 500 to your daily 2000 calories for an estimated maintenance caloric target of 2500 calories. If you prefer not to carefully track your intake during diet breaks, you can also consider aiming for a range, e.g. 2300-2700 calories per day or 200-250g carbohydrates per day, instead of a specific number.
Sometimes a full mental break is highly beneficial. If you think you need more of a mental break than a typical diet break offers, you can also implement untracked meals, as described below.
3. Untracked Meals
Untracked meals can offer many of the benefits of refeeds and diet breaks with the added benefit of giving yourself a break from meticulously tracking your food intake. Some may prefer to take untracked days rather than untracked meals.
This approach is certainly not for everyone. If you tell someone who’s been dieting to eat whatever he/she wants, the results could be disastrous. For some, it is easy to overeat by thousands of calories after being in a severe caloric deficit. On the other hand, some will be so used to restricting their intake that they will not even increase to maintenance level.
Untracked meals may take practice, but, if implemented correctly, they can provide a needed break for the mind and body. In my experience, sometimes just letting someone abandon meticulously tracking their intake is enough to increase intensity and expenditure and subsequently push through the plateaus caused by adaptive thermogenesis.
4. Reverse Dieting
If you have pushed dieting to your limits and decided that it is time to end the diet, then “reverse dieting” is an appropriate strategy to combat adaptive thermogenesis. The basic idea behind reverse dieting is to slowly increase calories so that you do not gain fat too rapidly.
Remember that adaptive thermogenesis means that your body adjusts to reduced intake7. The goal of reverse dieting is to very slowly increase calories so that your body will react by increasing energy expenditure. Depending on how gradual you add calories back in, you might even continue to lose weight while reverse dieting.
Those who have dieted to very low levels of body fat and testosterone and other hormones might benefit from a faster exit from their diet.
5. Eating Ad Libitum
Eating ad libitum basically means eating as much as you want of whatever you want. It might sound crazy, but eating ad libitum is actually a strategy to overcome adaptive thermogenesis.
However, you will likely see some weight (especially fat) gain with this method. Nevertheless, eating whatever you want without restriction can help your hormones and metabolism return to normal levels after dieting.
If you’ve been restricting your intake to lose weight and your progress has reached a plateau, you might need to implement a strategy to combat adaptive thermogenesis.
If you need weekly energy boosts, try refeeds. If you’re feeling exhausted but don’t feel ready to end the diet, you might want to try a diet break. If you are experiencing negative side effects of dieting but also driving yourself crazy tracking intake, you can try untracked meals. If you feel like you absolutely cannot take the diet any further, it might be a good idea to reverse diet. You might also want to consider ending your diet by failing to track what you eat altogether, or eating ad libitum.
For all of the methods discussed, one of the greatest benefits is the positive psychological impact of giving yourself a break from the diet mindset. Even if you do not work with a nutrition coach, think about a coach encouraging you on as you implement any of these approaches. If your brain knows that you have more food coming in via a refeed, diet break, untracked meal, or exit from your diet, you might suddenly have more energy not only for your workouts but for all of your activities.
Although there are methods that have been proven to help overcome adaptive thermogenesis, research is still emerging in this area. The “gold standard” study design of a randomized controlled trial is difficult and expensive to conduct in humans.
Additionally, the presence or absence of a direct effect in a controlled experiment does not mean that there will be a corresponding presence or absence in real life, where we are exposed to social and environmental factors that can impact our behaviors and health. Thus, you might have to use a trial-and-error approach to figure out which method is most effective for you.
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- Müller MJ, Bosy-Westphal A. Adaptive thermogenesis with weight loss in humans. Obesity (Silver Spring). 2013;21(2):218-228. doi:10.1002/oby.20027
- Fernández-Formoso G, Pérez-Sieira S, González-Touceda D, Dieguez C, Tovar S. Leptin, 20 years of searching for glucose homeostasis. Life Sci. 2015;140:4-9.
- Hall KD. A review of the carbohydrate-insulin model of obesity. Eur J Clin Nutr. 2017;71(3):323-326. doi:10.1038/ejcn.2016.260
- Dirlewanger M, di Vetta V, Guenat E, Battilana P, Seematter G, Schneiter P, Jéquier E, Tappy L. Effects of short-term carbohydrate or fat overfeeding on energy expenditure and plasma leptin concentration in healthy female subjects. Int J Obes Relat Metab Disord. 2000;24(1):1413-8.
- Friedman J. The long road to leptin. J Clin Invest. 2016;126(12):4727-4734. doi:10.1172/JCI91578
- Rosenbaum M, Leibel RL. Adaptive thermogenesis in humans. Int J Obes (Lond). 2010;34(0 1):S47-S55. doi:10.1038/ijo.2010.184