Fidgeting Can Fight Fat

Summarized by Robert W. Griffith, MD
May 25, 2005

Introduction

People become obese when energy input exceeds energy output. That's about as simple as it gets. And avoiding obesity is a question of reducing energy intake (calories eaten) and/or increasing energy output (e.g. exercise). But people differ a lot in their ability to keep their weight steady.

A recent study published in the journal Science has demonstrated what many of us could have worked out for ourselves: overactive people will lose weight more easily, just because they move about a lot more, and expend more energy. However, it's reassuring (and interesting) to have it put on a scientific basis, and maybe the findings will lead to behavior that can help obese people lose weight.

What was done

The result of changes in posture and movement that are associated with the routines of daily life, and is not the result of exercise, is called non-exercise activity thermogenesis, or NEAT. Researchers at the Mayo Clinic, Rochester, Minnesota, studied one of two components of NEAT, that which is associated with posture (standing, sitting, and lying). (The other component of NEAT was that associated with movement, i.e. ambulation.)

Ten lean (body mass index or BMI ~23) and 10 mildly obese (BMI ~33) sedentary volunteers were recruited; they were all self-proclaimed 'couch potatoes'. They were instructed to continue their usual daily activities while having their movements measured every half-second for 10 days.

The total NEAT of each participant was measured using a blood test employing a stable radioisotope. Body fat content was measured by dual x-ray absorptiometry.

After the first round of testing, 7 of the obese participants were asked to undergo a supervised weight loss program for 8 weeks, and the 10-day tests were repeated. Similarly, 9 of the lean volunteers underwent a supervised over-eating program for 8 weeks, and were then tested again.

What the study showed

The obese volunteers were seated for just over 2 hours longer each day than the lean volunteers, while the lean volunteers were upright (i.e. standing) for 152 minutes longer each day than the obese volunteers. There were no differences between the men and women in this respect. Obese and lean participants spent about the same time lying down.

It was calculated that, if the obese participants had the same posture allocation as the thin ones (i.e. the same periods spent sitting, standing and lying), they would have expended an additional 350 calories each day.

Total body movement was greater in those subjects with less body fat, and vice versa.

After the weight loss/weight gain program, the obese participants lost 8 kg (17½ lbs) and the lean participants gained 4 kg (9 lbs) before they were tested again. After these weight changes, the subjects had the same posture allocations - sitting, standing and lying - as before. This indicates that the differences in posture allocation are not caused by obesity.

What should we deduce from this small study?

The fact that obese people sit around more than thin people is not really very surprising. What is surprising, though, is that obese people who lose weight and thin people who gain weight still have the same non-exercise activity as they had before their weight changes. It seems that some chemical or hormone is slowing the activity level in obese people, which continues after they have lost weight.

This small study will certainly lead to other, larger, trials to see what factors can affect NEAT, and hence obesity. If you don't want to wait for their outcome, however, and are worried about being overweight, you can apply the concept. Hide the TV remote control, so that you have to get up from your chair at intervals to change the channel. Help your spouse by clearing the table after a meal. Park at the far end of the parking lot, take the stairs instead of the elevator, etc. By small acts of will, overcome that central something that decides how much you need to move when you're not actually exercising.

Source

• Interindividual variation in posture allocation: Possible role in human obesity. JA. Levine, LM. Lanningham-Foster, SK. McCrady,  et al., Science, 2005, vol. 307, pp. 584--586

Related Links
How Much Exercise Is Needed to Lose Weight?
What to Do About Excess Weight
Too Much TV is an Unhealthy Habit

Please take a moment to give us your comments. For questions about Health matters you may check our "Questions & Answers" Portal and Service.