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It's sad, but usually true: most people who lose weight eventually gain at least some of it back - and all too many gain back more than they lost. As you might expect, preventing that bounce-back and helping people to maintain their weight loss is becoming an important part of research into overweight and obesity.
Exercise Really Is Key to Weight Loss and Maintenance
A couple of years ago I reported on a study that showed the importance of exercise in achieving and maintaining weight loss (News Bite, 11/03/06). At a minimum, the National Institute of Health and the Center for Disease Control recommend thirty minutes per day of exercise on most days of the week, or 150 minutes per week. Studies also show, however, that the difficulty is not really in losing the weight - it's in keeping it off for the long term. How much exercise is necessary to help maintain weight loss?
Keeping It Off
We all know that it's one thing to lose weight - and quite another to keep it off for the long term. A study funded by the National Institute of Health and published recently inJAMA (2008;299(10):1139-1148) compares two strategies people might use to help maintain their weight loss: regular personal contact with a counselor via telephone or unlimited access to an interactive weight maintenance website. Could an online program take the place of an actual human being for the purpose of helping people maintain their weight loss?
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Yes, weight loss (and gain) is all about the calories: to lose weight, calories out (burned) must be more than calories in (eaten). Exercise is a great way to make sure that you burn more than you eat, and the current federal recommendation is for 150 minutes a week (that's 30 minutes per day, 5 days a week) of moderate exercise for "substantial health benefits." (Note that does not say "weight maintenance.") The Institute of Medicine, on the other hand, recommends 420 minutes per week (60 minutes a day, 7 days a week) of the same, moderate, level of exercise to help avoid becoming overweight or obese. Which is really going to help you maintain your weight - let alone lose weight?
A team of Harvard researchers made use of information collected in The Women's Health Study, which comprised almost 40,000 women followed for over twelve years (JAMA 2010;303(12):1173-1179). For the purposes of their study, they excluded women who reported having cancer or heart disease and those whose initial assessment did not include information about how much and how often they exercise.
On that initial assessment the participants reported the average amount of time each week they spent in eight different activities: walking/hiking, jogging/running, bicycling (including stationary bikes), aerobics (including using exercise machines), yoga/stretching, tennis/racketball, and swimming laps. For each of these types of exercises the researchers calculated the average metabolic equivalent (MET: a means of standardizing the number of calories an individual burns exercising) and then added them all together for each individual to estimate how many calories each person burned through exercise each week.
They then grouped the women into three levels of moderate-intensity exercise: < 7.5 MET hours per week (<150 minutes of exercise per week), 7.5 to <21 MET hours per week, and 21 or more MET hours per week (420 or more minutes of exercise per week).
Through regular reports throughout the original study, the participants reported on their weight, as well as their dietary habits and other factors. Using this information and cross-referencing it with how much exercise each woman reported doing at the time, the researchers were able to assess the relationship between Body Mass Index, weight gain and exercise.
All of the women gained some weight over the course of the study, regardless of how much they exercised. Compared to those who exercised the most, the women who exercised the least (<7.5 MET/week) were 14% more likely to gain at least five pounds over the course of the study. The really interesting result is this: the women who maintained a normal weight (BMI less than 25) throughout the study and never gained more than 5 pounds at any point averaged 21.5 MET hours per week of exercise over the course of the study.
If your Body Mass Index is within normal range, simply maintaining your healthy weight, while following a normal diet, appears to require 60 minutes of moderate exercise a day. If you're already overweight, don't despair! Combine a sensible eating plan from The Dr. Gourmet Diet Plan with increased moderate exercise. You'll reach your weight goal and you'll learn how to eat well and eat healthy.
First posted: March 31, 2010