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“It’s all about the calories. So long as the energy deficit is the same [with or without exercise], body weight, fat weight and abdominal fat will all decrease in the same way.” Eric Ravussin, MD, Pennington Biomedical Research Center, Louisiana State University (Reuters)
“If you just want to look thin, then maybe dieting is enough. But if you want to actually be healthy, then exercise has to be an important component of your lifestyle.” Dr. Jimmy Bell, professor of molecular imaging, Imperial College, London (AP)
Calorie Reduction With and Without Exercise
Why Spot Reducing Doesn’t Work
A study first published online January 2, 2007 in the Journal of Clinical Endocrinology & Metabolism found that diet and exercise are equally effective for reducing body weight and fat. That may be true, but it's not the whole story.
A team of researchers from the Pennington Biomedical Research Center at Louisiana State University, led by Eric Ravussin, MD, randomly assigned 35 overweight men and women to one of three groups for six months: 12 reduced calorie intake by 25%; 12 cut calories by 12.5% and increased their activity level by an equal amount; the remaining 10 served as controls and made no changes. Dual-energy x-ray absorptiometry (DEXA) testing at the end of the 6-month period showed no difference between the diet-only group and the diet-plus-exercise group. Both lost about 10% of their bodyweight, 24% of their fat mass (more for men and less for women), and 27% of their visceral fat (again, more for men and less for women) .
“A novel finding was that fat depots, regardless of their location, were reduced in such a way that fat distribution throughout the whole body and specifically within the abdominal compartment was not altered,” the researchers said. Overall fat distribution did not change in either group.
Unfortunately, spot reducing doesn’t work. We can’t pick and choose where on our body fat comes off.. This explains why sit-ups alone will not produce a six-pack. Sit-ups strengthen the abdominal muscles, but do not improve visibility without an overall reduction in body fat. “Individuals are genetically programmed for fat storage in a particular pattern” Dr Ravussin told Reuters, “and this program cannot easily be overcome.” Fat burn follows the same pattern, in reverse. Fat generally accumulates around the belly first, and comes off the belly last. (Women tend to accumulate fat on their hips and thighs.)
In this study, exercise didn’t protect muscle, and dieting alone didn’t cause muscle loss. Both groups lost roughly 13 pounds of fat and about 4.5 pounds of fat free mass (muscle). (Women in the diet-only group lost slightly more muscle.)
The form of exercise, I believe, may have affected the results. Participants were given a choice of treadmill, stationary cycle, or stairmaster. Making progressive resistance training part of the regimen might have protected or added muscle , giving the exercise group an edge. Perhaps weight training will be a part of a future study.
The researchers acknowledge that the study would need to be repeated with an exercise-only group to fully assess the impact of exercise on body composition and fat distribution. They observe, however, that creating a 25% energy deficit with exercise alone would be “a daunting task.” A 25% reduction in calories is, of course, no picnic—and probably unsustainable. As the researcher obviously appreciated, a combination of diet and exercise is more pleasant and effective for long-term weight control. Adding weight training might make it even more interesting and effective.
Some earlier weight-loss interventions by either diet or exercise, according to the researchers, have shown that exercise produced a greater reduction in fat mass. This issue apparently deserves more study.
In order to encourage compliance, the participants in the current study were allowed to “self-select their level of exercise intensity.” This may have also played a part in the result. “Exercise intensity has been shown to influence body composition…in a dose-response manner,” the researchers acknowledge. “Studies suggest that high-intensity exercise leads to greater improvements in visceral fat loss,” they add.
Importantly, the researchers specifically acknowledge the importance of exercise in their concluding comments: “Exercise plays an equivalent role to calorie reduction in terms of energy balance; however, it can also improve aerobic fitness, which has other important cardiovascular and metabolic implications.” (Emphasis mine.)
A London researcher not involved in the Pennington study has some important insights on body composition and exercise. Dr. Jimmy Bell, a professor of molecular imaging at Imperial College, has scanned nearly 800 people with MRI machines to create “fat maps” showing were people store fat, according to reporting by AP Medical Writer Maria Cheng.
Thin Outside, Fat Inside
His imaging studies show, Bell told Cheng, that apparently thin people are often fat on the inside. “Being thin doesn’t necessarily mean you’re not fat,” said Bell. Isn’t that really what the Pennington study found? We’re not told the exact details, but the distribution of fat of the two groups (diet and diet+exercise) was unchanged after the 6-month intervention. The subjects had less fat, but in all the same places; they were simply smaller versions of their former selves. Many of the subjects were probably still fat.
“Of the women scanned by Bell and his colleagues, as many as 45 percent of those with normal BMI scores (20 to 25) actually had excessive levels of internal fat,” Maria Cheng writes. “Among men, the percentage was nearly 60 percent.”
Bell calls these people “TOFIs,” or “thin outside, fat inside.” According to Cheng, he has even found professional models in this category.
TOFIs, Bell asserts, don’t exercise enough to burn off the fat inside--and become fit and healthy.
“Doctors theorize that internal fat disrupts communication systems,” Cheng reports. “The fat enveloping internal organs might be sending the body mistaken chemical signals to store fat inside organs like the liver or pancreas. This could ultimately lead to insulin resistance, type 2 diabetes, or heart disease."
As explained in articles 91 and 142 in the Fitness & Health category on this site, being unfit and being overweight are both primary risk factors on par with smoking, high cholesterol, and high blood pressure.
Like the Pennington researchers, Bell believes that exercise, combined with diet, is vitally important. “If you just want to look thin, then maybe dieting is enough” Bell told Cheng. “But if you want to actually be healthy, then exercise has to be an important component of your lifestyle.”
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