Advertisement UExpress LIFE PARENTING HOME PETS HEALTH ASTROLOGY ODDITIES A-Z SEARCH Ask the Doctors by Eve Glazier, M.D. and Elizabeth Ko, M.D Latest Archives HEALTH Junk Food Cravings Tied to Hormones, Circadian Cycle by Eve Glazier, M.D. and Elizabeth Ko, M.D ASK THE DOCTORS | NOVEMBER 15TH, 2021 Dear Doctors: Is there some reason I crave junk food when I’m really tired? I’m working double shifts, and if I don’t sleep enough, all I want is donuts and pizza. My husband says it’s because they’re my favorite foods and they’re easy, but it feels different than just that. What can I do? Dear Reader: You’re not imagining things when it seems that the allure of sweet and fatty foods gets stronger when you’re tired or run down. Research has found a link between sleep and our endocrine system, and the connection plays out with two hormones in particular: ghrelin and leptin. Each has an important role in the regulation of hunger. Ghrelin, which stimulates appetite, is produced and released mainly from the tissues of an empty stomach. It has many roles, including facilitating fat storage, regulating blood sugar and helping with memory retention. Most important in this context, though, is that it makes you feel hungry. In fact, despite ghrelin’s many other duties in the human body, it has come to be known as the “hunger hormone.” Leptin, by contrast, suppresses appetite. It is stored in adipose tissue, which is commonly known as body fat. Once released, it circulates in the blood and reaches the brain. One of leptin’s jobs is to signal the brain to create the feeling of being full after eating. In addition to certain triggers that are associated with food intake, the daily ebb and flow of these two hunger hormones is tied to the daily cycle of daylight and darkness. That’s the 24-hour period we know as the circadian cycle, which cues so many of the body’s essential functions. When you’re sleep-deprived, you’ve fallen out of sync with your circadian rhythms. This has the effect of suppressing the leptin levels that let you know you’re full and increasing the secretion of ghrelin, which amps up appetite. The result can be the spike in hunger you’re feeling that’s making sweet and fatty foods so tempting. Past research has found a link between sleep deprivation and an increase in the production of neurotransmitters known as endocannabinoids. These particular neurotransmitters also play a role in scent and feeding behavior, and can lead to an increased feeling of hunger. Another answer arises from an intriguing study from Northwestern University. Researchers found that the olfactory system -- the sense of smell -- goes a bit haywire in people not getting adequate sleep. A sharp increase in sensitivity to scents was followed by muddled brain messaging related to energy needs. The researchers suspect this could lead to a craving for energy-dense foods. With that kind of internal signaling, donuts and pizza would easily win when competing with salads and fresh fruit. No wonder we reach for the takeout menu and the snack drawer when we’ve missed out on sleep! While the occasional comfort food “cheat” is fine, we think you’ll feel a lot better with healthier fare. Plan ahead with meals that include high-quality protein and complex carbs, which will help you feel full and satisfied. (Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.) VIEW COMMENTS HEALTH 'Menopause' Has Both Specific and General Meanings by Eve Glazier, M.D. and Elizabeth Ko, M.D ASK THE DOCTORS | NOVEMBER 12TH, 2021 Dear Doctors: Can you please talk about the change of life for women? I have two grown daughters, and one of them went through it at a very young age. Why would that be? This part of a woman’s life doesn’t get a lot of attention, but it seems like it’s important. Dear Reader: When you refer to “the change of life,” you’re talking about menopause. Quite specifically, it’s the point at which a woman has gone a full year without having a menstrual cycle. These days, however, the word is used in a more general sense. It encompasses the many physical, mental and emotional changes that lead up to, and accompany, this major transition. This period of time, which is more accurately known as perimenopause, begins years before the actual moment of menopause. For many women, it occurs between ages 45 and 55, a time during which the ovaries slow their production of hormones, most notably estrogen. READ MORE HEALTH Many Breastfeeding Mothers Lose Weight by Eve Glazier, M.D. and Elizabeth Ko, M.D ASK THE DOCTORS | NOVEMBER 10TH, 2021 Dear Doctors: I’m breastfeeding my 4-month-old son, and I’ve lost some weight. I’m naturally thin, but my sister thinks my baby is not getting the nutrients he needs. The pediatrician says my son is doing great, but I’m worried. Do I need to switch to formula? Dear Reader: When a new mom is in good health and eating a balanced and well-rounded diet, her breast milk has everything that a baby needs to grow and thrive. Breast milk not only contains fat, protein and carbohydrates, but it provides the infant with vitamins and minerals, as well as water for hydration. It’s also a source of a range of important bioactive compounds that help to train and strengthen the baby’s developing immune system and aid in brain development. Breast milk is easily digested and absorbed, both significant factors for an infant’s brand-new digestive system. And the act of breast feeding can be an important part of building a bond between mother and infant. READ MORE LOAD MORE ARTICLES Next up: More trusted advice from... My Wife Has A Crush On Her Boss. Is She Going To Cheat On Me? 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