Exercise: Key ingredient
By Nanci Hellmich,USA TODAY

How much physical activity do you need to do to lose weight and improve your health?
- Most experts recommend at least 30 minutes a day of moderate-intensity activity for health benefits, but many say 45 to 60 minutes is necessary if you're trying to lose weight and keep it off.

- Today, in the seventh week of USA TODAY's eight-week Weight-Loss Challenge, we look at the importance of exercise.

- The challenge has been running each Monday this summer, offering expert advice and a variety of menus and recipes.

- It's not too late to start; no signup is needed. Choose your own diet plan or follow our low-calorie menus.

Researchers know people can lose weight simply by eating less. But now several new studies show how effective physical activity can be for weight loss and maintenance.

Ideally, people who are trying to lose weight should exercise for 30 to 60 minutes a day and eat a well-balanced diet, says Robert Ross, a professor in exercise physiology at Queens University in Kingston, Ontario. He has spent several years studying this issue.

In one study, Ross and colleagues assigned overweight men to one of four groups: a control group that made no changes, a group that tried to lose weight through diet alone, a group that tried to lose through exercise only (daily walking for 60 minutes) and a group that exercised without attempting to lose (eating more calories to make up for what they'd burned off).

The diet group and the weight-loss exercise group had similar deficits: about 700 calories a day. At the end of the three months, the participants in the two weight-loss groups had lost similar amounts of weight — about 16½— and had reduced abdominal fat, thus decreasing waist circumference. (The non-weight-loss exercise group also reduced abdominal fat, although not nearly as much as the others.)

Compared with the diet group, the weight-loss exercise group lost more overall body fat, preserved lean muscle and had improved fitness. Ross recently published a study that found similar results in women.

"If you have two people, both who lost 10% of their weight — one through just caloric restriction, the other through an increase in exercise — the person who is just exercising gets more beneficial results," he says.

"Physical activity is good for you. Period. Any weight-loss recommendation that excludes 30 to 60 minutes of physical activity is foolish and misguided."

Another study shows how important exercise is for keeping off pounds. Successful long-term losers from the National Weight Control Registry, a group of more than 5,000 people who have maintained an average 67-pound weight loss for more than six years, exercise 60 to 90 minutes a day.

Sixty minutes may seem like an overwhelming amount to someone who is sedentary, Ross says, but it can be accumulated in short 10-minute bouts over the course of the day, and it can be something as simple as brisk walking.

Another way to measure movement is by wearing a pedometer and counting steps. Some researchers and public health officials have encouraged people to take 10,000 steps a day, roughly five miles. On average, people walk about 5,310 steps in a day. A mile is about 2,000 to 2,500 steps, depending on your stride, and burns about 100 calories, depending on your height and weight.

In addition, weight training helps preserve and build muscle and is especially critical for people as they age, Ross says.

For those who want to cut calories while they add 30 to 60 minutes of physical activity to their daily routine, Ross recommends trimming no more than 500 calories a day.

If the rate of weight loss exceeds one to two pounds a week, it is likely that the loss includes lean tissue (skeletal muscle), he says.

Building muscles

Resistance training, including lifting free weights, working out on weight machines and doing push-ups, helps build lean muscle, which increases the number of calories the body burns.

Lean muscle is like a car engine. It burns the gas, or in this case calories, and provides the power. The bigger the engine, the more fuel the car burns. The larger the lean muscle mass, the more calories your body burns at work and at rest.

A person might gain a couple pounds of muscle in five to six weeks of intense exercise, says Tufts University fitness researcher Miriam Nelson. She says beginners should use light weights until they learn correct form, then steadily work up to heavier weights. " If you feel like you are plateauing, ask yourself, 'Can I lift more weight with good form?' If the answer is yes, go up; if not, stay where you are."

 

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