Showing posts with label appetite. Show all posts
Showing posts with label appetite. Show all posts

Monday, February 27, 2012

Sleep restriction leads to increased activation of brain regions sensitive to food stimuli.

Sleep restriction leads to increased activation of brain regions sensitive to food stimuli.


Feb 2012

Source

Institute of Human Nutrition, College of Physicians and Surgeons, Columbia University, New York, NY.

Abstract


BACKGROUND:


pidemiologic evidence shows an increase in obesity concurrent with a reduction in average sleep duration among Americans. Although clinical studies propose that restricted sleep affects hormones related to appetite, neuronal activity in response to food stimuli after restricted and habitual sleep has not been investigated.


OBJECTIVE:


The objective of this study was to determine the effects of partial sleep restriction on neuronal activation in response to food stimuli.


DESIGN:


Thirty healthy, normal-weight [BMI (in kg/m(2)): 22-26] men and women were recruited (26 completed) to participate in a 2-phase inpatient crossover study in which they spent either 4 h/night (restricted sleep) or 9 h/night (habitual sleep) in bed. Each phase lasted 6 d, and functional magnetic resonance imaging was performed in the fasted state on day 6.


RESULTS:


Overall neuronal activity in response to food stimuli was greater after restricted sleep than after habitual sleep. In addition, a relative increase in brain activity in areas associated with reward, including the putamen, nucleus accumbens, thalamus, insula, and prefrontal cortex in response to food stimuli, was observed.


CONCLUSIONS:


The findings of this study link restricted sleep and susceptibility to food stimuli and are consistent with the notion that reduced sleep may lead to greater propensity to overeat. This trial was registered at clinicaltrials.gov as NCT00935402.


American Journal of Clinical Nutrition

Saturday, February 11, 2012

Carbohydrate Addiction

Carbohydrate Addiction

What causes carbohydrate and other food cravings?

We don't really know enough about all the factors that cause specific food cravings. More research is needed to help understand appetite. Many studies suggest that a decrease in blood sugar stimulates hunger. This might help explain a craving for foods high in carbohydrates, which are a quick energy source.

Other studies suggest that the “mind-mood-food connection” may be explained by decreases in the brain chemical serotonin (sair-oh-TO'nin). Serotonin helps you feel less pain, less anxiety and less stress, so it improves mood by increasing relaxation. Some experts think that people who crave carbohydrates have low serotonin levels. Others caution that these cravings may just be a learned response.

What is “carbohydrate craving” or “carbohydrate addiction?”

These terms are used in a theory about the relationship between carbohydrate, insulin and appetite. (The body uses the hormone insulin to convert sugar, starch and other foods into energy.) We know that eating carbohydrate raises insulin, which then lowers blood sugar. This causes a desire (or craving) for more food and, in some people, carbohydrate.

Some people advocate severely reducing carbohydrate intake to reduce the insulin response and cravings. Others suggest that choosing carbohydrate-containing foods with a lower glycemic (gli-SE'mik) index also can lower insulin response and appetite. There isn’t enough research in this area for us to know what’s right. Also, individual responses may vary considerably.

What are the potential problems of severely reducing carbohydrate intake?

Diets low in carbohydrate are likely to lack sufficient amounts of essential nutrients found in plant foods that promote good health. People following these diets may not get enough vitamins, minerals and fiber to avoid blood chemistry imbalances, constipation and other health problems.

What's missing if carbohydrate-containing foods are severely restricted?

The American Heart Association recommends choosing a wide variety of foods low in saturated fat and cholesterol. While people need to watch their calorie intake to prevent obesity, they should consume a diet rich in grains (6 or more servings of breads, cereals, rice, pasta and beans) and at least five servings of fruits and vegetables daily. Combined with 2–4 servings of fat-free or low-fat dairy products, most healthy diets will contain at least 50–55 percent of calories from carbohydrates. Diets severely restricted in carbohydrate may be low in components that we need. For instance,

Diets low in grain products are likely to be low in B vitamins and minerals. Whole grains are also rich sources of potassium and fiber.

Low-fat or fat-free milk and yogurt are excellent sources of calcium, protein and riboflavin.

Vegetables and fruits are rich sources of vitamins, minerals and fiber. They may also have other components with health benefits that are still being discovered.

Some experts stress the importance of eating breakfast and at least two other meals a day to help control hunger. People with insulin resistance or diabetes may need to spread their calories out over a whole day by having small meals and 2–3 small snacks. (This can also help reduce hunger.) Related AHA publications:

An Eating Plan for Healthy Americans

Easy Food Tips for Heart-Healthy Eating

Reading Food Labels: A Handbook for People with Diabetes, order from American Diabetes Association (1-800-232-3472) Detailed Research

AHA Scientific Statement: AHA Dietary Guidelines: Revision 2000, #71-0193 Circulation. 2000;102:2284-2299; Stroke. 2000;31:2751-2766

See also:

Carbohydrates and Sugars Whole Grains and Fiber American Heart Assoc. - Nutrition Center Healthier Kids Fiber and Children's DietPhytochemicals and Cardiovascular Disease Triglycerides Vegetables and Fruits Vegetarian Diets Carbohydrate Addiction

Diet and Lifestyle Recommendations