The complicated world of hormones, from the gut to the brain, plays a pivotal role in how hungry or full you feel, how efficiently you metabolize food, and where fat lands on your body. That affects the success you have at losing and maintaining weight, especially as you get older. By understanding how hormones do their jobs, you get a better overall picture of the weight loss landscape. Here's a lineup of hormones that play a role in weight control.
Produced by fat cells, leptin is involved with eating and appetite regulation. The level of leptin in your body is directly proportionate to your body fat; more body fat means more leptin in your blood. Here's the catch: The more fat you accumulate, the less responsive your body is to leptin, so your brain doesn't get the "stop eating" message as strongly. Researchers are investigating leptin's role as an appetite regulator and trying to determine ways to alter the mechanism. For now, the best thing you can do is build more muscle mass and decrease fat tissue by becoming physically active. This will help your body be more responsive to its leptin signals.
This oddly spelled hormone signals hunger and tells the brain it's time to eat. Ghrelin levels rise shortly before you eat and diminish once you're full. Blocking ghrelin production to reduce hunger feelings is one avenue researchers are investigating as a potential way to control appetite. Ghrelin is produced in the stomach and, according to a study in the New England Journal of Medicine, impaired ghrelin levels (in addition to a smaller stomach) may be one of the reasons why people who have had gastric bypass surgery can be satisfied with much smaller quantities of food; their hunger signals have been rewired or bypassed.
Everyone knows insulin control is critical for people with type 1 diabetes, but insulin also dictates how efficiently you metabolize food, whether you have diabetes or not. It also acts together with leptin when calories increase to initiate the "stop eating" message. As you acquire more fat, the body becomes insulin-resistant, meaning insulin cannot properly get energy (glucose) into the cells. Blood sugar levels rise out of control, sometimes resulting in full-blown diabetes. That's why weight control acts as one of the first lines of defense against diabetes. By maintaining a normal weight, you remain insulin-efficient and avoid further health complications.
The sex hormones estrogen, progesterone, and testosterone play critical roles in reproductive health, and they also have a role in weight gain, especially as you age. Have you noticed how many women in midlife go from being a pear shape (carrying weight in the thighs and buttocks) to an apple shape (packing more pounds around the abdomen)? This shift in weight distribution is often attributed to hormonal change. Both aging and menopause are associated with changes in fat metabolism and may contribute to midlife weight gain.
The Female Sweet Tooth
While this isn't a hormone in itself (though it can sometimes feel that way), there is some science behind the propensity for women to crave sweets. Ever wonder why you can polish off some desserts and candy during certain times of the month? Your craving for sweets may be related to the female hormone estradiol, according to a study published in the American Journal of Physiology.
Although the study was done with rats, the animal data suggest that the female preference for high-carbohydrate, sweet foods during the menstrual cycle may be influenced by hormonal changes.
It seems men prefer to chow down on high-protein, high-fat, salty foods, such as steaks, chips, and chili con queso, while women prefer another slice of pie.
Though it may seem unfair that this happens to you and not the men in your life, take heart. Your estradiol levels will go down, and you won't be in the grip of your hormones all month. There is also research that indicates physical activity may lessen the impact of this hormone, so plan extra walking during your high-risk time of the month.
What You Can Do About Hormone-Related Weight Gain
The internal, intricate pathways created by hormones aren't completely out of your control. "The most important thing for holding off midlife weight gain is getting some form of regular exercise," says Jane Harrison-Hohner, associate professor and women's health nurse practitioner at the Oregon Health & Science University School of Nursing in Portland. "Study upon study finds a healthful diet, combined with exercise, to be key to weight control."
Researchers have also identified other hormones that regulate appetite. A better understanding of the role that hormones play in stimulating and controlling appetite may lead to the development of medications that assist weight loss and maintenance.