Diet Tips

Weight loss is all about calories in vs. calories out. But sometimes it's not that easy. The tips in this section were submitted by readers, and include a few of our own favorite ways to stay on a healthy weight-loss plan. Check back often for new and fresh ideas to jumpstart your diet, or help you get through those little hurdles along the way. Have a tip to share? Send it to us!

Diet versus Exercise for Weight Loss

Karen Collins, MS, RD, CDN
American Institute for Cancer Research

With excess weight a greater problem than ever, the question of whether changing eating habits or exercise is more likely to produce weight loss is vital. A new study confirms the overall research findings that dietary change specifically eating less fat produces more weight loss than changes in exercise. But it also shows that changes in one kind of behavior may help promote changes in the other, especially among women.

Many studies have compared weight loss resulting from changing diet versus increasing activity. Most often, weight loss during programs focused on dietary change produced two to three times greater weight loss than programs focused on exercise.

However, it’s long-term results that matter for our health. One analysis of many such studies showed that by one year after the end of these programs, there was no significant difference in the weight status of participants. This raises the question of whether people can maintain changes in exercise more easily than changes in eating habits. The answer, of course, almost surely depends on individual preferences as well as how unpleasant or enjoyable the attempted diet or exercise program was.

We become overweight when we consume more calories in food and drink than we burn up. To lose weight, we need to shift that balance and burn up more than we consume. We can accomplish that by consuming fewer calories, burning more, or both. Cutting calories doesn’t necessarily have to mean going on a “diet.” It can just mean avoiding or limiting one or more foods high in calories from fat (such as high-fat meat, cheese, or snack foods, or too much added fat), lots of sugar (like sweets or sweetened drinks), or alcohol. Cutting calories can also be accomplished by reducing our portion sizes, or by eating smaller portions of those high-calorie foods and filling up on larger portions of low-calorie vegetables and fruits.

Objective analysis shows that cuts in calorie consumption add up faster than increases in exercise. Studies show that a combination of smaller portions and changes in what we eat can easily add up to reduce calorie consumption by 500 daily, whereas burning an extra 500 calories daily can be a daunting target.

In this new study conducted at the University of Minnesota, moderate or substantial drops in dietary fat were linked to weight loss in overweight and obese men and women, regardless of how much they changed physical activity. On average, these successful program participants decreased the number of high-fat foods they ate by five to ten servings a week. In women, even substantial increases in exercise were not enough to produce weight loss if they did not decrease fat consumption. Men, however, were able to lose weight through increased exercise alone. This might be because the men were able to burn more calories in exercise than women, or might reflect either some metabolic difference or a problem in the study’s ability to detect changes accurately.

For men, the effects of exercise and dietary fat seemed to have independent effects on the amount of weight lost. For women, although exercise alone was not a successful weight loss strategy, at each level of dietary fat reduction those who increased exercise − moderately or substantially − lost more weight than those who changed activity less.

Whether exercise changes metabolism to allow more successful weight loss, or whether its stress-reduction benefits allow more consistent progress in changing eating habits, this and other studies show that both increasing exercise and decreasing calorie consumption clearly seems the best weight-loss choice for everyone.

Weight Loss Requires More Than Cutting Fat

Karen Collins, MS, RD, CDN
American Institute for Cancer Research

After years of being unsure whether cutting back on dietary fat is the key to weight loss, the public is now more confused by the recently released results of the Women’s Health Initiative (WHI). This study seems to suggest that fat in the diet doesn’t matter at all. Justifiably, many people are wondering how much fat consumption does affect weight control.

One part of the WHI study looked at how the weight of 19,000 post-menopausal women was changed when they were told to follow a lowfat diet. The women were supposed to reduce their dietary fat to only 20 percent of their calories. Most women did not get very close to that low goal, but they did progress from diets that averaged 38.8 percent fat (rather high) at the beginning to diets with 29.8 percent fat (which is considered a lowfat diet) at the end. To see if fat consumption alone can influence weight, these women were instructed to eat more carbohydrates as they cut back on fat to try to maintain their initial weight. At the beginning of the study, 74 percent of the women were overweight or obese.

Because of its setup, the study was able to answer two separate questions. First, does eating less fat for better health lead to weight gain if you eat more carbohydrates? The answer turned out to be no. You can cut back on fat without fear it will lead to weight gain. However, to achieve health benefits you should focus on decreasing saturated and trans fat consumption.

Second, can people lose weight by cutting back on fat without changing their exercise habits or trying to reduce calories? For the group of women over age 50 in this study, the answer was no. Like these women, if you cut fat in your diet but substitute other foods to maintain the same calorie intake, you shouldn’t expect to lose weight.

Women in the WHI study on the lowfat diet reportedly reduced their calorie intake by an average of about 360 calories a day, which should have led to a significant weight loss. However, these women lost less than two pounds in seven years. Perhaps, the women inaccurately reported what they ate. Or, perhaps, their drop in calorie intake was only enough to prevent weight gain. To induce weight loss, they may have needed to do more, since we all tend to become less active with age and our metabolisms tend to slow.

For people already at a healthy weight who want to avoid the usual adult weight gain that increases the risk of several cancers, the modest fat and calorie reduction that women on a lowfat diet achieved in this study may be enough. However, other studies show that many adults need 45 to 60 minutes of exercise a day to avoid overweight. The women in the WHI study had a wide range of activity levels, but they averaged only the equivalent of walking for 30 minutes at a moderate pace, six days a week.

For overweight people who want to control their weight, this study suggests you should do more than adopt a lowfat diet. Working in blocks of activity that add up to an hour a day seems to help.

However, creating enough of a change in your balance of calories consumed and burned to produce weight loss almost always requires eating fewer calories. Eating less fat, without increasing calories from other sources, is one way to do this. If you currently eat few vegetables, fruits, whole grains and beans, eating more of these foods may help fill you up enough that you can cut down on foods more concentrated in calories from fat and sugar. But in today’s world of enormous servings and constant food availability around the clock, studies suggest that without consciously cutting back on your portion sizes and unnecessary eating, simply eating more healthy food like vegetables and fruits is unlikely to cause weight loss.

Future studies can test whether the conclusions of the WHI study apply to men and younger women. But it’s reasonable to assume that increasing activity and eating fewer calories will help everyone.