Hormones and Weight Loss: Diets based on deprivation don’t work. While it’s well-known in research that this is the case, most of us don’t need to read an academic article to know this is true. We’ve either seen or experienced the endless diet cycle that over-restricts calories, inevitably leading to frustration and weight regain.
If you are following a weight loss program that tells you exactly what foods to eat, you will probably lose weight. But what happens after one month, six months, or a year? Does the weight loss continue? Do you continue to see positive health benefits?
In general, diets focusing only on cutting calories for weight loss don’t produce long-term benefits. People can lose weight, but they can’t keep it off. Or they plateau and give up because they stop seeing results, leading to an unhealthy cycle of dieting and regaining. Sometimes over and over again, damaging metabolism and, possibly even worse, leads to a feeling of failure or blame that the person following the diet didn’t have enough willpower to keep going.
The truth is any diet “failure” has little to do with willpower and much more to do with the body compensating for changes. This doesn’t mean you have no control over what happens when you lose weight, but it does mean you have to be smart about how you do it – and work with your body instead of fighting against it.
Hormones and Weight Loss: Why is long-term weight loss so difficult to achieve?
You may have heard about the “set point” theory, where every person has a “set” weight that the body wants to maintain. In reality, the body doesn’t necessarily want to stay heavier. Still, biological adaptations occur very soon after weight loss and continue to persist even up to one year after a person gains back the weight.
Some of these compensatory mechanisms include:
- Hunger and satiety hormones: Certain hormones in the body help signal to our brain when we are full or when we are hungry. They can stimulate an increase in appetite or tell us to push away the plate if we are full. Diet changes and weight loss affect these hormones.
Our first example is leptin. Leptin is a hormone that tells the brain that it’s time to stop eating when we are full or satiated. Restricting calories significantly lowers the amount of leptin circulating in the body. This means that when someone follows a calorie-restricted diet, leptin will affect the ability to regulate appetite and feelings of fullness. This makes sense because if the body thinks it is not getting enough nutrients, it is smart enough to turn on the message that you need to eat more.
Leptin has been studied in animal models where deficiencies lead to obesity. A human study that looked at leptin levels over a twelve-week weight loss program found that leptin levels dropped significantly by week three and continued to be lower than those following a normal diet through the end of the program. Even after the women in this study could normally eat again, leptin remained significantly lower for more than seven weeks. Another study found that leptin levels remained considerably below baseline after 62 weeks. Again this means that people who have lost weight through caloric restriction have somewhat lost the ability to self-regulate their satiety signals.
Conversely, hormones that signal to increase appetite can increase with weight loss. Ghrelin is a hormone that stimulates hunger and is known to increase circulation with weight loss associated with low-calorie diets. Ghrelin increases in circulation before meals stimulating appetite. In the same study on women mentioned above, ghrelin levels increased until week ten when they dropped slightly – but remained higher than baseline by week.
If dieting increases a hormone that makes you hungry and decreases a hormone that helps you feel full, is it any wonder that people have a hard time losing weight?
- Metabolic adaptations: When you lose weight, your metabolism drops. As a result, the amount of calories you burn over 24 hours significantly decreases, and this lowered energy expenditure can last for more than a year. This means that your body will work to hang on to the remaining weight by reducing your metabolism. And similar to leptin and ghrelin, this reduction in metabolism can last even if you regain the weight, making it harder to lose weight in the future.
Each of these adaptations occurs because the body wants to conserve resources. Low-calorie diets that last for weeks can lead to stress in the body. If the body is stressed, it will shift into survival mode. But if low-calorie diets aren’t the answer to weight loss – what can you do instead?
Low-Carb and High-Carb to support (not fight against) biological adaptations
Low-calorie diets are not the answer to long-term weight loss. But eating the standard American diet of high-calorie, processed food is not working either. So what can we do instead?
If we take a step back and consider why the body is forced to make these adaptations – we can use our biology to our advantage. Low-calorie diets work initially, but then they fail. Even beyond the physiological reasons listed above, they take away the joy of eating, are challenging to follow, and are not long-term realistic.
The answer to this problem is a well-planned cyclical pattern of low-carb, intermittent fasting, and high-carb days.
- Kelesidis, Theodore et al. “Narrative review: the role of leptin in human physiology: emerging clinical applications.” Annals of internal medicine vol. 152,2 (2010): 93-100. doi:10.7326/0003-4819-152-2-201001190-00008
- Gruzdeva, Olga et al. “Leptin resistance: underlying mechanisms and diagnosis.” Diabetes, metabolic syndrome and obesity : targets and therapy vol. 12 191-198. 25 Jan. 2019, doi:10.2147/DMSO.S182406
- Ahima, Rexford S. “Revisiting leptin’s role in obesity and weight loss.” The Journal of clinical investigation vol. 118,7 (2008): 2380-3. doi:10.1172/JCI36284