For anyone who has ever tried to lose weight and keep it off, you know that it’s not an easy feat. In fact, many people succumb to the difficulty of maintenance and find themselves not only gaining the weight back, but additional pounds on top of that.
We know the deal with weight loss, but what about after? After committing so much time to extensive hard work and discipline, why would someone simply gain it all back? Considering the initial weight loss, it’s clearly not a lack of willpower. Sometimes all it takes is one little cheat day to act as a trigger. But such a small thing shouldn’t have so much power.
It just doesn’t make sense.
More research is being done on the changes that the body goes through after weight loss. It turns out that there’s a lot more to it than we initially assumed – go figure.
A study published in the American Journal of Clinical Nutrition found that those who have maintained weight loss for more than a year experience a decrease in energy expenditure. Remember, carbs in particular are used as energy. The less energy you have to spend, the less you want to do – or more you want to eat.
What’s the deal with that? Why does it take your body so long to adjust itself to this new weight and diet? A study that was published in the New England Journal of medicine set out to explore that question. Specifically, it examined whether the changes that occur in appetite-regulating hormones during weight loss are sustained with prolonged maintenance of reduced weight1.
There were 50 participants in this study, but only 34 met all of the requirements by the end, and only results from those 34 people were used. Those participants lost 10% of their body weight in a 10 week period. Over the course of a 62 week period, participants followed a recommended diet, exercise routine, and were provided with nutrition counseling.
Also over that 62 week period various components of appetite were tested before and after meals – once at the beginning of the study, again after a 10 week period, and finally at the 62 week mark. Body measurements were made, participants provided self-reported ratings of their appetites, and blood tests were taken.
It was found that the average of leptin levels decreased by about 65% while participants were in a “hungry” state (before breakfast). Why’s this significant? Leptin is a mediator of long-term regulation of energy balance, suppressing food intake and thereby inducing weight loss2.
In other words, the hormone that balances energy and suppresses food intake was, on average, less present after weight loss than when participants were at their baseline weight. Leptin isn’t the only hormone that peripherally modulates appetite. Others include ghrelin2, cholecystokinin3, peptide YY4, insulin5, pancreatic polypeptide6, and glucagon-like peptide 17. There are many factors that go into regulating your appetite – all of which are affected when you limit your caloric intake. Your body compensates with a decrease in energy and subsequently decreased levels of leptin, decreased cholecystokinin, and increased levels of ghrelin and overall increased appetite.
Together, these increases and decreases promote weight gain.
It’s understandable, then, that many people who lose a significant amount of weight tend to gain it back (and then some). This study is only a suggestion of what could be and probably is – much more research will need to be done to understand the exact science. For example, what would happen to participants who lost 15% of their body weight over the course of a year, rather than only 10% in only 10 weeks? There are still many unanswered questions, but encouraging to have the beginning of an answer.