Have you ever watched a skinny person down a plate of French fries and still have room for dessert – all without gaining a pound? You probably chalked their good fortune up to a metabolism as fast as a hummingbird’s or simply good genetics. While genetics certainly play a role in how easily a person gains weight, a study published in the journal Science casts a different light on why some people seem “immune” to weight gain even when they overeat.
Eat More, Waste More Energy?
In this study, 16 normal-weight volunteers ate a diet containing 1,000 more calories a day than their body needed to maintain their weight for 2 months. The participants were told to maintain a low level of activity – no 5-mile runs or weight-training sessions at the gym.
At the end of the 2-month study, as might be expected, the participants gained weight, but the amount of weight they gained varied by as much as 10 pounds between individuals. One participant gained less than a pound while the participant who put on the most weight gained almost 10 pounds. Why such a wide variation in weight gain?
Although their basal metabolic rate increased by only about 5% as a result of overeating, this wasn’t enough to explain why some of the subjects gained so little weight. What the researchers found was that non-exercise activity thermogenesis went up significantly in the lucky individuals who gained the least amount of weight.
What is Non-Activity Thermogenesis?
Non-activity thermogenesis or NEAT is the calories you burn when you’re not working out at the gym, sleeping or eating a meal. It includes the low-intensity activities you do throughout the day like taking a shower, playing video games, washing dishes or simply fidgeting. For most people, NEAT accounts for most of the energy, they burn over the course of a day.
Researchers believe the reason some individuals in this study gained less weight when they overate was that they expended more energy through NEAT. In other words, they fidgeted more and were more active in a low-intensity sort of way without consciously being aware of it. In fact, one individual burned almost 700 additional calories per day through NEAT, and they were one of the participants who gained little despite eating an additional 1,000 calories per day. There was an inverse correlation between NEAT and the amount of weight the subjects gained.
“Good Genetics” May Be Partially Explained By NEAT
Some individuals naturally ramp up their activity without being aware of it when they splurge and eat a double-cheese pizza and wash it down with a milkshake. They fidget more, do things faster and increase their activity level in general. Chances are you’ve met more than one skinny person who just couldn’t seem to sit still. They may be unconsciously burning off that doughnut they just ate. This goes back to the idea of a set point weight that your body tries to maintain. When you eat too much, you move around more to maintain your weight. When you lose weight by dieting and go too far below your set point, you move around less, fidget less and expend less energy to move back towards your set point weight.
The Bottom Line?
NEAT is not something you’re consciously aware of, but that doesn’t mean you can’t consciously increase the amount of non-exercise activity you do throughout the day. Retrain yourself to get up and move around every 15 minutes instead of staying glued to your chair. Stand and move around when doing activities you’d normally do sitting such as talking on the phone and working on the computer. Avoid elevators, and pick up the pace when you walk or wear a pedometer to motivate yourself to take extra steps. Don’t assume because you work out at the gym you can relax in an easy chair for the rest of the day. NEAT accounts for a significant number of the calories you burn each day. Make them count.
References:
Science. 283(5399): 212-4. (1999)
Layman’s Journal of Hyperplasia Research. “Non-Exercise Activity Thermogenesis”
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Maintaining a Lower Body Weight After Weight Loss
Weight Maintenance: New Study Shows How Your Body Works Against You
How Non-Exercise Activity Affects Weight Loss
5 Ways to Burn More Calories at Rest
5 Factors That Increase the Risk of Weight Regain After Weight Loss
Move More! Every Minute of Activity Counts Towards Weight Loss
