The Perennial Weight Loss Question: Exercise Or Diet?

Which matters more when it comes to losing weight, diet or exercise? Let's take a common sense look at the most frequently asked question about losing weight.

Dieting Makes a Critical Difference in Weight Loss

There is a lot to be said for the theory behind dieting, for simply restricting calories, to lose weight. It's a matter of math. Cut out 3500 calories, lose a pound of fat. (Or cut out 7700 kcal, lose a kilogram of fat, for those who prefer the metric system.) The principle is very straightforward. Actual calorie counting isn't.

Let's say you weigh 220 pounds (100 kilos). You have a penchant for potato chips. You can't eat just one, as the old marketing slogan used to say. You always eat the whole bag of potato chips, the whole 1400 calories of chips. Being health-minded, however, you vow to burn those calories off on the elliptical machine in your basement.

Since you weigh 220 pounds, you aren't going to do a high-intensity workout, but that's OK, since slow workouts burn fat, right? You just have to exercise long enough to burn off those tasty potato chips you love to eat.

How long does it take someone who weighs 220 pounds to burn off 1400 calories at a leisurely pace on an elliptical machine? The calorie meters on elliptical machines are notoriously unreliable. How you set the tension on the machine makes a big difference, as does whether you do interval training, short bursts of intense physical activity in the middle of a longer routine. However, if you weight 220 pounds, you can burn off 1400 calories in two hours or less even if you use the easiest setting and even if you work out very slowly.

That's two hours of exercise every time you eat a bag of potato chips, or two chunks of cake, or four pieces of fried chicken, without rewarding yourself with even more food after you do the workout, and without "forgetting" to complete the entire exercise routine. If you like to eat, you need to exercise, a lot, several hours a day, to lose weight, without compensating for exercise by eating more. But let's suppose you are really disciplined.

We Need to Eat Fewer Calories to Lose Weight, But How Do We Really Know the Calories in Food?

Let's suppose you are a disciplined dieter who isn't going to eat a whole pie or a whole bag of chips (or at least not two) or a bucket of fried chicken and French fries. You know you are eating too much, but you know you can count calories or— can you?

Calorie counting involves websites, databases, handbooks, and math even after you measure your food. Eyeballing what you eat doesn't really work. You really need to use measuring cups and scales to know how much food you are really eating. Once you measure your food, you need to look up the calorie content and do the calculations that tell you the number of calories in it. 

READ Calorie Count At McDonald's - Are You Lovin' It?

Let's suppose you are dedicated and smart and you can do the intellectual work of monitoring your calories. Your non-dieting friends and family patiently wait to eat while you are measuring your food (fat chance, most people would say). Then the problem is that all those websites, databases, and handbooks can be 25 to 35 percent off. The moisture content of your food makes a large difference in the number of calories it contains. Labels aren't always accurate. You could be eating too many calories to lose weight or too few to avoid hunger despite all your efforts.

Getting Around the Calorie-Counting Problem

There are a couple of ways to get around the problem of counting calories. One is to go for one of the macronutrient-restricted diets, a diet that restricts protein or a diet that restricts fat. The problem with those kinds of diets is that they tend to be unsustainable. 

Another way to get around the calorie-counting problem is to let a diet center do the calorie-counting for you. Jenny Craig, Weight Watchers, and Nutrisystem all promise to count your calories so you don't have to. If you are extremely overweight, this may be the right way to go, provided you can stick to the program. When the instructions for frozen weight loss dinners say you can supplement the frozen dinner with a salad, for instance, they don't mean a bacon-and-fried-chicken Cobb salad with extra cheese and three cups of salad dressing plus a Twinkie. Supervised weight loss programs seem to have a lot going for them, or do they?

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.