Light Therapy and Winter Weight Gain
Carbohydrate Cravings and Winter Weight Gain
The shorter days of fall and winter causes changes in the metabolic activity of mammals that can result in altered behavior. In all mammals digestive activity normally triggers a sense of "fullness" in the brain after eating. In fall and winter the signal from the gut that triggers a sense of satiety in the brain is suppressed in the evening. This is how nature encourages mammals to increase food intake and gain weight in order to survive cold winter weather and a scarcity of food. More.
Humans, being mammals, also experience seasonal changes in body chemistry. In winter a delayed sense of satiety leaves many people feeling hungry in the evening. Even after a large dinner they do not feel satisfied and want to keep eating, especially sweets and starches. This phenomenon has been termed "carbohydrate craving".
It is common for people living in temperate latitudes to gain between five and ten pounds every winter. Studies show this weight gain results from snacking in the evening, while daytime eating patterns do not appear to change. Refs.. Carbohydrate craving contributes to the failure of most weight loss programs in winter and is one of the major complaints of people who are subject to Seasonal Affective Disorder (SAD) or the Winter Blues. See Refs.
Using Light Therapy to Combat Winter Weight Gain
In humans the signal of seasonal change is the length of day as registered by the biological clock in the brain. Keeping the body in a summer mode with light therapy gives affected people added energy and lighter spirits. It also eliminates the evening carbohydrate cravings which can contribute to winter weight gain. Refs.