ALTERED EATING HABITS

ALTERED EATING HABITS. The quantity and types of foods consumed, however, may be the most important determinants of the obesity epidemic. Over the last few decades, eating patterns have changed in wealthy countries. Both the quantity of foods consumed and the energy density of the foods consumed have increased over the past 30 years. For example, in 1970, the average energy intake for adult men was 2,450 calories per day. By the year 2000, calorie intake had increased to 2,618. At the same time, consumption of energydense foods also increased.

Energy density is the number of calories in a gram of food. (One gram equals about 0.035 ounces. A teaspoon of sugar weighs about 4.2 grams.) Fats, with 9 calories per gram, are much more energy dense than either carbohydrates or protein, at 4 calories per gram. High-fat diets are common in wealthy countries, often because of eating restaurant foods, prepackaged take-out meals, or fast foods. Fast-food meals, for example, are often 40% fat and very high in calories.

Snacks and sweets also contribute to high fat intake. Candy and potato chips, for instance, often have a high fat content. We have inherited tastes for sweet and fatty foods from our ancestors. The preference for sweet tastes, as opposed to bitter or sour ones, probably evolved as a defense against eating toxic plants or contaminated and spoiled foods, which often have a decidedly un-sweet taste. Humans came to crave sweet foods, and because they rarely found enough food to overeat, they were not harmed by their cravings. In a similar way, our bodies came to crave fatty foods because they were both rare and energy dense. Early humans needed to store as much energy as possible, and fats provided the most efficient energy storage. Sugars are quickly metabolized into glucose and energy. Fats and carbohydrates could mean the differencebetween survival and starvation. Now, even though fatty, sweet foods are plentiful, many people continue to prefer fat and sweet foods over many others.

Portion sizes have changed dramatically over the last few decades, and most people have accepted and learned to eat large portions of foods. In 1957, for instance, an average serving of soda was 8 ounces (0.2 liters). Today, it can be 64 ounces (1.9 L). A box of popcorn at the movies in 1957 held about 3 cups. Today, the average medium serving is 16 cups. An average muffin in 1957 weighed 1.5 ounces (42 g). Today it is 8 ounces (227 g). The same differences in portion sizes are found in meals and snack foods. A fast-food hamburger in the 1950s contained only about 1 ounce (28 g) of meat; a large hamburger served in a typical restaurant today may contain 6 ounces (170 g) of meat, and some supersized hamburgers weigh more. One study found that, since 1977, everyone—both children and adults—increased portion sizes of all types of foods, whether eating out or at home.

Sherwood and her colleagues believe that several factors have contributed to the increases in portion sizes and intake of fatty, sweet foods. They cite television advertising for candy, snacks, sugary cereals, pizza, and fast foods. For children, they point to family eating practices, parental role modeling, and the decrease in the number of meals that families eat together. For both children and teens, the researchers advocate combating these trends with school-based educational programs about healthy nutrition and programs and opportunities for physical activity.efer fat and sweet foods over many others.

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