"Why am I constantly hungry?" is a question I hear from many of my patients. At best, constant hunger is annoying and distracting; at worst, it's a sign that something's amiss. Either way, the mental wrestling can make it hard to trust the messages your body is sending you. Assuming that you're eating regularly throughout the day, there are several possible explanations why hunger might be a constant companion.
Your body has biological mechanisms in place to keep your weight from dropping below your set point — the weight range you are genetically predisposed to maintain — whether you are experiencing famine or what just looks like a famine (a.k.a. calorie-restricted dieting). One is a drop in your resting metabolic rate. The other is an increase in appetite.
Even though the body needs fewer calories as weight decreases, hunger and the drive to eat increase. In fact, increases in appetite may play a more important role than a slowing metabolism in weight-loss plateaus. For each kilogram (2.2 pounds) of weight lost, we burn about 20 to 30 fewer calories per day — even fewer for some people — whereas appetite grows by about 100 calories per day. Basically, it's easier for your body to protect itself by boosting your appetite — and your calorie intake — than to slow your metabolism and run on fewer calories.
Of the three macronutrients — carbohydrates, protein and fat — protein contributes the most to satiety, the feeling that you've eaten enough. That doesn't mean you should go overboard on protein — you need the nutritional variety from all three macronutrients — but making sure to include some protein in each meal and snack may keep you satisfied longer. That could be eggs, yogurt, tofu, beans, fish, chicken or meat. Experiment to see how you feel after eating different meals.
Your gut, and the microbes that dwell in it, act as a "mini brain," influencing, among other things, mood, appetite and food cravings. The tens of trillions of bacteria and other microbes in our gut produce a number of compounds, including some that are identical or similar to appetite hormones. About 20 minutes after a meal, certain bacteria in your gut send signals that you've had enough to eat by stimulating the release of a hormone that has been linked to feelings of satiety. But if you don't have a very diverse microbiota — the microbe population living in our intestines — other species can become dominant, and what they need to survive and thrive may be different from what your body needs.
When you and a dominant group of microbes aren't on the same page, they will try to manipulate your eating behavior for their benefit. They may cause cravings for their preferred foods, or for foods that suppress their competitors. They may simply increase your hunger levels until you eventually eat what they want you to eat. Either way, this creates a vicious cycle. For example, if you eat a lot of sugary foods, "sugar-loving" microbes will thrive, whereas microbes that don't do so well on sugar may weaken or die. Because the sugar-loving microbes are well-nourished, they'll gain even more influence, increasing sugar cravings.
Support a diverse microbiota by eating foods rich in fiber and probiotic bacteria, being physically active, handling stress and getting adequate sleep. This reduces the chance that any single species will have the numbers to gain an upper hand, and may help reduce food cravings and unusual hunger.
Chronically skimping on sleep can lead to increased hunger and carbohydrate cravings, possibly because of the loss of REM (rapid eye movement) sleep. Results of a 2015 study published in the journal Sleep Medicine suggest that the loss of our final REM sleep cycle of the night may lead to a bigger appetite. If you get less than six hours of sleep, take note: The final REM cycle begins around the six-hour mark.
There are many opinions, expert and otherwise, about the optimal number of daily meals and snacks. However, there is no clear, consistent evidence that links meal timing or frequency with weight or health. Your ideal meal frequency will give you steady energy throughout the day and let you get hungry enough between meals that you feel ready to eat a nourishing meal but not so hungry that you are ready to eat the first thing you see. Experiment with your meal frequency to see what feels right for you, remembering that you don't want to eat so frequently that you never feel hunger.
Many people have lost touch with their hunger signals. They may have a long-standing habit of skipping meals, or of constant grazing. They might be a chronic dieter, or have a chaotic home or work life. Each of these scenarios can silence hunger signals over time. When you don't feel, or can't identify, true hunger, you may mistake other urges to eat — including cravings, emotions or the need for stimulation — for hunger.
Dennett is a registered dietitian nutritionist and owner of Nutrition by Carrie.