When it comes to hunger signals, there's one hormone called ghrelin that dominates the rest, and being able to regulate it more efficiently is key to reducing belly fat. How can you send it spiking the right way? By losing weight, according to a new study in the Journal of Clinical Endocrinology&Metabolism.
Researchers looked at nearly 300 participants who were in the obese classification of body mass index. All had lower fasting ghrelin levels compared to those in the normal weight classification, which is common among those carrying excess weight. Lower ghrelin is associated with high blood pressure and a larger amount of belly fat, as well as a higher body fat percentage overall.
Participants were split into three groups that had different diet approaches, but all combined that with regular physical activity. All three groups resulted in weight loss, no matter which diet was used, and participants saw a significant increase in their ghrelin levels. This led to lower abdominal fat and, subsequently, improved insulin sensitivity. Those who followed a Mediterranean diet that included leafy green vegetables and green tea—and avoided red meat—saw the biggest ghrelin surge.
"These results suggest that weight loss in itself can change ghrelin levels in a positive way and that decreases health risks like developing diabetes or other metabolic diseases," the study's senior author, Iris Shai, Ph.D., adjunct professor of nutrition at the Harvard T.H. Chan School of Public Health told Eat This, Not That! She adds that they also noted benefits in terms of gut health and reduced liver fat, which are also crucial for lowering chronic disease risk.
If you've lost weight, how do you know if your ghrelin is on track without getting a hormone test? Better awareness of hunger and fullness.
Sometimes called the "hunger hormone," ghrelin tells you when to eat and it's produced by the cells in the stomach as a signal to the brain. Throughout the day, the hormone rises and falls, sometimes dramatically, and usually is at its lowest level after eating.
Its compatriot hormone, leptin, is the one that produces feelings of satiety and sends signals to stop eating and to start burning calories. Perhaps counterintuitively, when you have obesity, leptin tends to be high and ghrelin is low, which seems like it would be a beneficial arrangement—except that it impairs appetite regulation.
When both are on track after weight loss, you tend to have better control of these processes, and that improves metabolism overall, says Shai.