A Scientific Test Of Calorie Restriction Versus Exercise For Weight Loss

There is a stream of scientific evidence that people who go to commercial weight loss centers for diet advice lose more weight, more of their waistline, and more fat mass than people who go it alone. The difference at the end of a year isn't all that much. One study found that people who go for weekly meetings and weigh-ins on average weigh 2.8 kilos (about 6 pounds) less than those on self-managed diets. The difference at the end of two years, however, is striking. People who manage their own diets usually gain all their weight back before two years have passed, while people who continue to go to commercial weight loss centers usually keep most of their weight off.

Is it best to diet to lose weight or to work it off at the gym?

Researchers Stephen Ball and Ann Bolhofner, both faculty at the University of Missouri at Columbia, recruited 43 overweight women for a formal study of exercise versus diet. These women were exactly the kind of women most gyms and weight loss programs target in their advertising.

• Their average age was 41.
• Their average body fat was 40 percent.
• They were all sedentary, that is, they got less than 60 minutes of exercise per week.
• Their average weight was 176.4 pounds (80.2 kg).
• Their average height was 5'4" (162.9 cm).

The researchers then gave all 43 women a gift certificate for either Weight Watchers or to Gold’s Gym and and Gold’s “Quick Start” exercise program in exchange for their participation in three sets of measurements.

For those who may not be familiar, the Weight Watchers program, recently promoted by Oprah Winfrey, emphasizes:

1. An integrated approach to weight loss that emphasizes healthy eating choices, good eating habits, a supportive environment for making personal changes, and exercise.
2. A plan that allows participants to eat what they like, with an emphasis on staying satisfied by choosing the foods they enjoy while making sure to meet nutritional needs.
3. A "sensible plan" to help Weight Watchers lose weight at a healthy pace with the knowledge and needed for keeping it off for good.
4. A "time-tested approach informed by analyzing years of scientific studies."
5. Flexible food plans that can be adapted to individual preferences and needs.

“Even though WW (Weight Watchers) promotes exercise,” the website says, “the major component of the program is calorie restriction.” Diet is the main emphasis of the Weight Watchers approach.

Gold's Gym offered the participants assigned to exercise three sessions with a personal trainer. The goal of these sessions was to make sure that each participant could:

1. Learn 8 to 10 exercises, which would

2. Take 10 reps to failure. That is, the trainer helped the women choose a weight or resistance setting that was high enough to ensure that they could not possibly do any more at the end of a routine (before they had to go on to the next exercise).

The women were told to do these exhausting exercises (exhaustion being part of how the exercises were expected to work) three times a week and to do cardio (walking, jogging, swimming, ellipticals, bike) three times a week. After the first three sessions, the women were expected to do all their exercise on their own.

The women who were in the gym program received instruction and supervision by trainers at the beginning of the program to ensure that they could do the exercises properly. 

Here's what happened:

• At the end of 12 weeks, the women in the Weight Watchers group had lost on average 4.1 kilograms (9 pounds), and all of them had lost weight. At the end of 12 weeks, the women in the Gold's Gym group had lost on average 1.3 kilograms (2.5 pounds), and some of them had gained weight.
• At the end of 12 weeks, the women in the Weight Watchers group had lost on average 1.1 percent body fat. At the end of 12 weeks, the women in the Gold's Gym group had gained on average 0.8 percent body fat.
• At the end of 12 weeks, women in both groups had lost fat-free ("muscle") mass, but the women in the exercise group had lost more.

Not only did the exercise-only program fail to reliably produce weight loss, it sometimes resulted in weight gain, and it even resulted in muscle loss. How could this be?

READ Extra Calories, And Not Their Source, Are Responsible For Body Fat

The researchers monitored numerous other variables, including food intake. While the women in the Weight Watchers group drastically reduced their consumption of carbohydrates, protein, and fat, the women in the Gold Gym's group, following the informal diet advice their trainers gave them at the beginning of the study, actually increased consumption of fat. Moreover, the heaviest women in the Gold's Gym group dropped out of the study altogether.

This study doesn't necessarily tell us that dieting will take off more weight than exercise, but it certainly seems to tell us that exercising on your own usually won't work. To be fair, dieting on your own usually doesn't result in long-term weight loss, either. The support you have as you lose the weight is critical. Just be sure that you follow a diet, that you keep even when you start to exercise.