Bright-light therapy may help weight loss

Tom Blackwell, National Post  Published: Monday, July 30, 2007

A simple device most often used to counteract severe cases of the winter blues also seems to help people shed disease-causing fat, a surprising new study concludes.

Obese and overweight subjects who coupled their exercise regimen with bright-light therapy lost significantly more body fat than those who exercised without the light boxes, say researchers at a Toronto hospital.

The "remarkable" results are an important step in efforts to maximize the benefits of exercise, in this case without even changing diet, say authors of the study, just published in the journal Obesity.

"To show that we actually have a way to reduce body fat after moderate exercise and an intervention is one of the most fascinating findings of this work," said Dr. Sharon Chung, one of the researchers at Toronto Western Hospital. "Too much fat around the gut ... ages us before our time. [But] it''s very hard to change our body fat."

The group, headed by Dr. Colin Shapiro, a Toronto Western psychiatrist, has plans for a larger study that will test the impact of the special bright-light lamps -- which filter out harmful UV rays -- on people who are overweight but not exercising, as well as those working out.

Deena Sherman, a 40-something Toronto photographer, said she had a sense of "wellbeing" during the study and did lose weight, but is not sure whether it was the light, or the fact the researchers ensured she followed a regular exercise routine.

Bright light therapy has been proven effective in treating patients with seasonal affective disorder -- depression that sets in during winter months when there is minimal sunlight.

One theory is that the lights affect levels in the brain of serotonin, a neurotransmitter which regulates emotion and behaviour, and may affect appetite as well.

The Toronto Western researchers divided their 29 initial subjects in two groups: Control subjects who would only exercise three times a week for 30 minutes at a time, and another bunch who would do the same workouts but also expose themselves to the light therapy for up to an hour a day.

After six weeks, both groups had lost some weight. The bright-light subjects also saw their body fat decrease to about 39% from 41% during the month and a half, while the other subjects'' fat percentage actually climbed slightly.

That is a "remarkable" change over such a short period, say the researchers, who received a small grant from Litebook Co., a maker of the light boxes.

Body fat is a key health issue, with so-called "visceral" fat around the abdomen an important risk factor for metabolic syndrome, a cluster of conditions that can include diabetes and high blood pressure.

 

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