By Candace Chemtob
Hunger is complicated. A Harvard endocrinologist explained it: “The fundamental role of hunger is to drive us to seek and consume food.” In the days when food was scarce, hunger was important to survival. But today, tempting foods are abundant and hunger can erode our willpower to eat healthily despite the best of intentions.
Research has helped us gain a better understanding of the physiologic basis of hunger, but we know little about how to best control hunger. Currently, there are very few effective pharmacologic and surgical options to blunt hunger. And even if there were more options, hunger is not a straightforward physiologic response to a food deficit. When and what we eat is influenced by emotions, food cues and other psychological factors. As anyone struggling with their weight knows firsthand, these factors exert a strong influence on our food choices.
Feeling hungry starts with an empty stomach. While you may have never heard of the hormone ghrelin, this hormone produced by the stomach is believed to be responsible for hunger pangs and growling stomachs. Ghrelin acts on the hypothalamus in the brain to stimulate the appetite. High levels of ghrelin can increase food intake by as much as 30%. Conversely, as you eat, ghrelin levels fall. When food enters the intestines, hormones and small proteins called peptides (GLP-1, cholecystokinin and PYY, to name a few) are released. For the most part, these intestinal hormones and peptides counteract the effects of ghrelin and suppress the appetite. Once food is completely broken down in the intestines and nutrients are released into the bloodstream, these nutrients themselves trigger metabolic cycles, stimulate insulin production and ultimately communicate with the brain to control hunger.
For decades, it was thought that adipose tissue was inert, simply a place to store excess fat. We now know that fat cells help regulate food intake. Discovered in 1994, leptin is a hormone secreted by fat cells that influences the appetite by signaling the brain. Leptin also plays a role in the regulation of body weight. Leptin levels are proportional to the amount of body fat. If you lose weight, leptin levels decrease and tell you to eat more. Research has shown that some obese individuals are leptin resistant, meaning that leptin is produced but its signal is ignored.
Although we have a long way to go in understanding hunger, here are some tips based on current research that may help you to curb your appetite:
- Overly processed, high carbohydrate foods make you hungrier. They cause rapid increases in blood glucose and insulin levels and may disrupt appetite suppression after eating.
- High fiber foods, such as fruits, vegetables, and whole grains not only reduce your risk for serious health problems such as heart disease, diabetes and cancer, but they may also help control your weight. Higher in fiber diets are associated with lower body weights. The assumption is that fiber adds bulk to your diet and fills up the stomach, but because humans cannot digest most fibers it has no calories.
- Get plenty of sleep. If you don’t sleep enough, you may be hungrier. Being sleep-deprived is associated with a preference for high calorie foods, overall higher caloric intake and gaining weight. It is hypothesized that the main hormones that regulate hunger are adversely affected by a lack of sleep.
- High protein meals may help you feel fuller for longer.
- Eating slowly decreases hunger and increases the feeling of fullness sixty minutes after eating.
- Exercise helps control hunger. Working out leads to changes in appetite, hunger, and energy intake, decreases the ghrelin levels and increases concentrations of leptin.