Doc Talk: Can’t lose weight? You might need more sleep

01/13/2014 3:21 PM

08/08/2014 10:21 AM

Troubling managing your weight? Lack of sleep may be the culprit.

It is no secret that our society struggles with excess weight and weight-loss resistance. Researchers at John Hopkins University estimate that by this time next year more than 75 percent of Americans will be overweight, with a staggering 41 percent of them classified as obese. Many blame the propensity to overeat and indulge in junk food on a lack of will power; however, science is now showing it may be related to hormones.

There are two hormones associated with food cravings and overeating: ghrelin and leptin. Research by sleep health experts reveals that healthy sleep cycles can help to balance these hormones.

Ghrelin is a hormone produced by the stomach during times of famine. Ghrelin stimulates hunger and digestive function. When we fast for several hours, our body begins to increase ghrelin production which interacts with the neurons in the metabolic control center of our hypothalamus, and we begin to feel hungry.

Leptin is a hormone secreted by our fat cells that interacts with the hypothalamus and creates feelings of fullness that shut down our hunger center. When we fast, ghrelin levels rise. When we eat, insulin and leptin levels rise and ghrelin levels drop. Higher levels of ghrelin have been associated with cravings for sugar-rich, calorie-dense junk food and, ultimately, weight gain.

Many people go on calorie-restricted diets in order to lose weight. However, calorie restriction can lead to dramatic increases in ghrelin secretion. This results in uncontrollable hunger and eventual overeating. Ghrelin is responsible for the classic starvation-binge cycle that ruins so many weight loss pursuits.

Researchers at Stanford University found that people who sleep five hours or fewer per night had a 15 percent greater amount of ghrelin and 15 percent less leptin than those who slept eight hours per night. Another study showed that sleep-deprived individuals had a significantly greater craving for carbohydrate-rich junk food.

Leptin and ghrelin work as a check-and-balance system to control feelings of fullness and hunger. Poor sleep cycles drive leptin down and increase ghrelin, resulting in less satisfaction after eating and craving more food. Over time the body can become leptin resistant, which virtually shuts down the body’s ability to effectively burn fat.

Studies show that sleep may be the most important lifestyle factor for weight loss. In addition to aiding with the balance of ghrelin and leptin, the sleep hormone melatonin has been shown to help heal leptin receptors and restore normal leptin sensitivity, which is critical for healthy weight loss and fat burning mechanisms in the body. Sleep deprived individuals do not secrete enough melatonin to restore normal leptin function.

Sleeping has also been shown to enhance human growth hormone (HGH) secretion, which is the body’s natural anti-aging hormone. HGH secretion stimulates growth and reproduction of cells. It enhances metabolism to burn fat, build muscle and boost immunity. Elevated insulin levels are not compatible with HGH. Therefore, eating food, particularly carbohydrate-rich foods, before bedtime is detrimental to efforts to effectively burn fat.

Growth hormone is released by the pituitary gland in episodic waves, about once every 90 minutes, with the strongest wave coming approximately one hour after you fall asleep. When released in amounts adequate to meet your physiological needs, growth hormone can help keep your muscles and bones strong and decrease the amount of adipose (fat) tissue that you carry. A lack of adequate growth hormone production is one of the chief reasons why people who do not get enough sleep tend to be at an unhealthy weight for their height and/or have weak muscles and bones.

Adequate sleep also supports the hormone erythropoietin, which is produced by the kidneys and stimulates the production of red blood cells by your bone marrow. Red blood cells deliver oxygen to, and carry carbon dioxide (waste) away from, every cell in your body. This hormone is responsible for strength, energy and stamina.

Testosterone is a steroid hormone secreted by the testicles of males and the ovaries of females. Adequate testosterone secretion is essential to a strong immune system, high energy and strong bones, and it helps reduce the risk of developing osteoporosis. If you do not get enough sleep on a daily basis, your body will still produce erythropoietin, growth hormone and testosterone; however, it just won’t produce amounts that will allow you to experience your best health.

In addition to feeling more rested, adequate sleep boosts collagen production – a protein that strengthens blood vessels and gives skin its elasticity – and lowers blood pressure and heart rate. Blood pressure needs to dip at night so your cardiac muscle and circulatory system have time to relax and repair. It’s especially important for people with high blood pressure to get at least seven hours of sleep to experience that temporary drop, which helps reduce the risk for heart disease.

So, how can you ensure a good night’s sleep? Here are few guidelines:

• Do not eat within three hours of sleep. If you must eat before bed, have good fat/protein such as cheese or yogurt.
•  Keep your bedroom cool (around 70 degrees F)
•  Keep your bedroom as dark as possible (light inhibits melatonin secretion).
•  Get moving during the day. Regular movement throughout the day helps burn off metabolic waste in muscles and cells, allowing the body to relax more effectively.
•  Avoid caffeine and stimulants after 3 p.m.

To learn more about sleep and weight management check these online sources:

• The Impact of Sleep Deprivation on Hormones and Metabolism: Medscape.com
• Your Guide to Healthy Sleep: NIH.gov

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