Ka Wai Ola - Office of Hawaiian Affairs, Volume 12, Number 3, 1 March 1995 — 'Ai pono, e ola [ARTICLE+ILLUSTRATION]

'Ai pono, e ola

Eat right and live well

by Dr. Terry Shintani

The ninth myth of dietina - "lt's all in the genes"

In the last two articles, I described eight diet myths. Here is what I eall the ninth myth. Have you ever heard anyone say that there's no use dieting because "It's all in the genes"? I've heard it many times as a reason someone gives for not losing

weight, or for not even trying - to change their diet. For some people, the rationale is that they have tried many diets and still gained all their weight back and more. Out of frustration, they begin to believe that their body weight is predetermined at birth and that there's nothing they ean do about it. The truth is that our body weight is partially

determined by our genes, or our heredity, but not totally. Our weight is determined to an even greater extent by our food and our activity. Genes determine our potentiaI range of body weight Our genetic makeup does play some part in determining our body weight. Genes are

part of long chains of organic material called chromosomes found in the nuelei of our cells that carry the biological information that determines what eaeh eell will be and do. We know that they play a part in determining our body weight because of a number of studies done in the 1970s.

I In one of these studies, a world-renowned researcher on obesity, Dr. Albert Stunkard, did an observational study at various fast food restaurants and snack bars where obese and slim customers were observed and their intake of food estimated. He found that the amounts eaten by obese peo- | ple were about the same as

the amounts eaten by slim people. Another researcher found that obese people may eat even slightly less than slim people. Another world-renowned researcher tried a different type of experiment to show that genetics had an effect. Dr. George Bray and Dr. Ethan Sims reported that university student volunteers were asked to see if they could increase their body \yeight by 20 per-

cent. To their surprise they found that despite their best efforts, they could not increase their weight by more than 10 percent. This is in sharp contrast to some individuals that seem to be able to gain massive amounts of weight (even into the 500- to 700-pound range) that most of us could not gain even if we tried. This strongly suggests that weight is determined by genetics. Diet and exercise determine where in that range we will be. If genetics is the sole determining factor, however, how do we explain the differences between the ancient Hawaiians, who were slim, and modern Hawaiians, who have one of the highest rates of obesity in the nation? How do we explain the fact that Japanese in Japan are genetically the same as those in Hawai'i but remain mueh slimmer than our Hawai'i Japanese? The answer appears to be in the differenee in the type of food eaten rather than the amount of food. None of the studies above tested what would happen if the type of food was changed. The type of food eaten in ancient Hawai'i and in Japan are

similar in fat content, about 10 percent of calories. Studies now suggest that if we eat a high-fat diet, we tend to have a high-fat body. If we eat a low-fat diet we tend to have a low-fat body. Thus, using the saying "you are what you eat" is quite accurate because we know that the type of food has an effect on determining our weight despite genetics. A final facet of the diet equation is the amount of exercise a person does. The more one exercises, the more a body tends toward leanness. Putting it all together, we ean see that our weight is partly in the genes, but also largely if not mostly in what we eat and what we do. With this understanding, I hope no one will ever give up trying to eat right and exercise, and I hope no one will ever give up while saying, "It's all in the genes." Terry Shintani, MD, MPH is a physician and nutritionist. He is the director of preventive medicine at the Wai'anae Coast Comprehensive Health Center. A majority ofits 20,000 clients are of Hawaiian ancestry.