Tuesday, September 13, 2016

A completely new way of thinking about weight loss

The Study
The prevailing wisdom about how to lose weight is to decrease calories and increase physical activity. This theory was put to the test in a very interesting study. One hundred and fifty four adolescents and 75 college age women underwent a two week baseline measure of their resting metabolic rate, energy intake, and body composition. Researchers created a variable for each subject called energy flux, which was calculated by adding energy intake and energy expenditure for each person. Subjects were then followed for 2 years to see who gained or lost the most weight.

The subjects with low energy flux were more likely to gain weight, while the subjects with high energy flux were more likely to lose weight. In other words, eating more calories and exercising a lot reduced the risk of gaining weight, while eating fewer calories and exercising very little increased the risk of gaining weight. American Journal of Clinical Nutrition 2016; 103:1389-96.

Take Home Message
This is a fascinating study that tells us 2 two things:

1) Exercise is extremely important for long term weight maintenance, which most of us already know.

2) Cutting calories a lot may not facilitate long term weight loss. This is a relatively new concept. 

Our body fights back really hard when we cut calories. Very few people can keep weight off long term when they lose it solely by reducing energy intake. The researchers believed that the reason the low energy flux group gained weight was largely due to significant decreases in resting metabolic rate as a response to the lower calorie intake.

Although this is just one study and more research is needed, it is becoming clear that weight loss is much more than just calories in versus calories out. The human body has awesome defense mechanisms to keep its body fat at what it considers to be a safe level. We have much to learn about these mechanisms.

I tell my weight loss clients to cut their calories slightly, not severely, and to make cardio and strength training a very consistent habit.

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