- Part 1: Women And Weight Gain After 40 - Part 1
- Part 2: Women And Weight Gain After 40 - Part 2
- Part 3: Women And Weight Gain After 40 - Part 3
Part 4: Weight gain and sleep
- Cortisol. Production of cortisol varies rhythmically throughout the day, being highest upon waking and declining to its lowest levels of the day at the time you typically go to sleep. Chronic, moderate sleep deprivation interrupts this diurnal cycle, causing end-of-the-day cortisol levels to remain high. Over time, elevated cortisol levels can lead to insulin resistance (the body’s inability to respond to insulin’s message to store nutrients), obesity and diabetes. Elevated cortisol levels are of particular concern to menopausal and peri-menopausal women, as the combination of high cortisol and low estrogen contributes to middle-of-the-body weight gain (aka the “muffin top”).
- Leptin. Secreted by fat cells, leptin is the satiety hormone, telling your brain when you’ve consumed enough calories and reducing appetite to prevent overeating. Leptin regulation is markedly affected by sleep duration. Chronic sleep deprivation results in lower circulating levels of leptin, increased appetite and higher caloric intake, even in the absence of increased physical activity (i.e., short duration sleepers have potentially more wakeful hours to be physically active; in the studies cited above, they weren’t, either because they chose not to be or their activity was restricted by the researcher). Given that many menopausal and premenopausal women experience insomnia and middle-of-the-night awakening, even those that attempt to get an adequate number of hours of sleep each night may not.
- Ghrelin. Working in opposition to leptin, ghrelin is secreted by the stomach and stimulates appetite. Short sleep duration is associated with elevated ghrelin production and increased hunger and appetite, in particular an appetite for foods high in carbohydrates (hello chocolate!). Similarly, declining estrogen levels (both during the period leading up to menopause and during the second half of the menstrual cycle in regularly cycling women) also trigger an increased appetite for sweet and starchy foods.
- Glucose tolerance. The sweet and starchy carbohydrates you consume are broken down, by the gut, into smaller, glucose molecules, to be used as fuel by our muscles and brain. Excess glucose is stored as fat, a process triggered by the release of insulin by the pancreas. Chronic short sleep duration results in a marked reduction in acute insulin response; glucose remains in the blood stream for a much longer period of time after consumption leading to a pre-diabetic state after as little as a week of sleep restriction.