Changes in Diet and Lifestyle and Long-Term Weight Gain in Women and Men

[Guest guest]

http://www.nytimes.com/2011/07/19/health/19brody.html?pagewanted=2 & _r=1

It's no secret that Americans are fatter today than ever before, and not just

those unlucky people who are genetically inclined to gain weight or have been

overweight all their lives. Many who were lean as young adults have put on lots

of unhealthy pounds as they pass into middle age and beyond.

It's also no secret that the long-recommended advice to eat less and exercise

more has done little to curb the inexorable rise in weight. No one likes to feel

deprived or leave the table hungry, and the notion that one generally must eat

less to control body weight really doesn't cut it for the typical American.

So the newest findings on what specific foods people should eat less often — and

more importantly, more often — to keep from gaining pounds as they age should be

of great interest to tens of millions of Americans.

The new research, by five nutrition and public health experts at Harvard

University, is by far the most detailed long-term analysis of the factors that

influence weight gain, involving 120,877 well-educated men and women who were

healthy and not obese at the start of the study. In addition to diet, it has

important things to say about exercise, sleep, television watching, smoking and

alcohol intake.

The study participants — nurses, doctors, dentists and veterinarians in the

Nurses' Health Study, Nurses' Health Study II and the Health Professionals

Follow-up Study — were followed for 12 to 20 years. Every two years, they

completed very detailed questionnaires about their eating and other habits and

current weight. The fascinating results were published in June in The New

England Journal of Medicine.

The analysis examined how an array of factors influenced weight gain or loss

during each four-year period of the study. The average participant gained 3.35

pounds every four years, for a total weight gain of 16.8 pounds in 20 years.

" This study shows that conventional wisdom — to eat everything in moderation,

eat fewer calories and avoid fatty foods — isn't the best approach, " Dr. Dariush

Mozaffarian, a cardiologist and epidemiologist at the Harvard School of Public

Health and lead author of the study, said in an interview. " What you eat makes

quite a difference. Just counting calories won't matter much unless you look at

the kinds of calories you're eating. "

Dr. B. Hu, a nutrition expert at the Harvard School of Public Health and a

co-author of the new analysis, said: " In the past, too much emphasis has been

put on single factors in the diet. But looking for a magic bullet hasn't solved

the problem of obesity. "

Also untrue, Dr. Mozaffarian said, is the food industry's claim that there's no

such thing as a bad food.

" There are good foods and bad foods, and the advice should be to eat the good

foods more and the bad foods less, " he said. " The notion that it's O.K. to eat

everything in moderation is just an excuse to eat whatever you want. "

The study showed that physical activity had the expected benefits for weight

control. Those who exercised less over the course of the study tended to gain

weight, while those who increased their activity didn't. Those with the greatest

increase in physical activity gained 1.76 fewer pounds than the rest of the

participants within each four-year period.

But the researchers found that the kinds of foods people ate had a larger effect

over all than changes in physical activity.

" Both physical activity and diet are important to weight control, but if you are

fairly active and ignore diet, you can still gain weight, " said Dr. Walter

Willett, chairman of the nutrition department at the Harvard School of Public

Health and a co-author of the study.

As Dr. Mozaffarian observed, " Physical activity in the United States is poor,

but diet is even worse. "

Little Things Mean a Lot

People don't become overweight overnight.

Rather, the pounds creep up slowly, often unnoticed, until one day nothing in

the closet fits the way it used to.

Even more important than its effect on looks and wardrobe, this gradual weight

gain harms health. At least six prior studies have found that rising weight

increases the risk in women of heart disease, diabetes, stroke and breast

cancer, and the risk in men of heart disease, diabetes and colon cancer.

The beauty of the new study is its ability to show, based on real-life

experience, how small changes in eating, exercise and other habits can result in

large changes in body weight over the years.

On average, study participants gained a pound a year, which added up to 20

pounds in 20 years. Some gained much more, about four pounds a year, while a few

managed to stay the same or even lose weight.

Participants who were overweight at the study's start tended to gain the most

weight, which seriously raised their risk of obesity-related diseases, Dr. Hu

said. " People who are already overweight have to be particularly careful about

what they eat, " he said.

The foods that contributed to the greatest weight gain were not surprising.

French fries led the list: Increased consumption of this food alone was linked

to an average weight gain of 3.4 pounds in each four-year period. Other

important contributors were potato chips (1.7 pounds), sugar-sweetened drinks (1

pound), red meats and processed meats (0.95 and 0.93 pound, respectively), other

forms of potatoes (0.57 pound), sweets and desserts (0.41 pound), refined grains

(0.39 pound), other fried foods (0.32 pound), 100-percent fruit juice (0.31

pound) and butter (0.3 pound).

Also not too surprising were most of the foods that resulted in weight loss or

no gain when consumed in greater amounts during the study: fruits, vegetables

and whole grains. Compared with those who gained the most weight, participants

in the Nurses' Health Study who lost weight consumed 3.1 more servings of

vegetables each day.

Other Influences

As has been suggested by previous smaller studies, how long people slept each

night influenced their weight changes. In general, people who slept less than

six hours or more than eight hours a night tended to gain the most. Among

possible explanations are effects of short nights on satiety hormones, as well

as an opportunity to eat more while awake, Dr. Hu said.

He was not surprised by the finding that the more television people watched, the

more weight they gained, most likely because they are influenced by a barrage of

food ads and snack in front of the TV.

Alcohol intake had an interesting relationship to weight changes. No significant

effect was found among those who increased their intake to one glass of wine a

day, but increases in other forms of alcohol were likely to bring added pounds.

As expected, changes in smoking habits also influenced weight changes. Compared

with people who never smoked, those who had quit smoking within the previous

four years gained an average of 5.17 pounds. Subsequent weight gain was minimal

— 0.14 pound for each four-year period.

Those who continued smoking lost 0.7 pound in each four-year period, which the

researchers surmised may have resulted from undiagnosed underlying disease,

especially since those who took up smoking experienced no change in weight.

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Carruthers

Wakefield, uk