Americans are getting wrapped up in weight watching. This past November, for example, three of the top 10 nonfiction bestsellers were how-to-lose-weight books. Add in weight-loss cookbooks, specialty dietary foods and supplements, and online diet clubs, and you’ll find that dieting in the United States is a multibillion-dollar industry.

Most popular diets recommend specific combinations of proteins, fats, and carbohydrates, demanding dieters eat more or less of some foods or even avoid others entirely. This can be tricky, considering many foods are a combination of all three.

Today’s typical American derives 50 percent to 60 percent of his or her food energy from carbohydrates, 25 percent to 35 percent from fats, and 15 percent from protein. A gram of protein or carbohydrate contains four calories, while a gram of fat contains nine. (A raisin weighs about one gram.) Approximately 3,500 calories—no matter the source—equals a pound. When you consume 3,500 calories beyond what you expend, you gain a pound. When you burn off 3,500 more calories than you consume, you lose a pound.

Power to the protein

On a high-protein diet, as many as half a participant’s total calories come from fat, and 30 percent to 40 percent from protein with carbohydrates strictly limited. Meat, poultry, eggs, fish, dairy, fats, and oils all are permitted. Consumption of this dietary balance typically leads to a process called ketosis, which can suppress the appetite, create a sense of well-being, and cause a quick weight reduction through the loss of water in the body.

Does it work? People lose weight on this diet. In fact, they often experience a quick weight loss. Because fat remains in the digestive system longer than proteins or carbohydrates, the higher consumption of fats leads to a feeling of satiety. “Low-carb” meals increasingly are offered in restaurants and grocery stores, so it is fairly easy to follow this diet. Some studies show that cholesterol is lowered along with weight. However, the high consumption of protein places an extra burden on the kidneys and is considered to increase the risk of osteoporosis, gout, and other joint-related diseases. High consumption of saturated fats contributes to cardiovascular disease, though there are no long-term studies about this specific diet. Also, carbohydrates are a primary source of dietary fiber, and low-fiber diets such as these can lead to chronic conditions, including constipation, diverticulosis, and colon cancer.

Low fat, high carbs

Some low-fat diets call for as little as 10 percent fat in the diet, with carbohydrates as high as 75 percent and protein at about the American average of 15 percent. The recommended carbohydrates are whole grains, fruits, and vegetables, rather than highly refined products. Plant proteins are preferred, and animal proteins generally are used in small amounts, almost as a condiment. In some cases, this diet is a transition to becoming vegetarian. Another plus is this diet is high in fiber. A recent study showed that people who eat a high-fiber diet are half as likely to become obese as those who eat a low-fiber diet.

Does it work? Long-term studies on variations of this diet have shown that followers lose weight and significantly improve their cardiovascular health. Many people find it easy to stick with this diet on a long-term basis, though it can be difficult to follow when eating out. The low-fat content can lead to feelings of hunger soon after eating, so people often snack during the day. The preference for complex carbohydrates results in a healthy high-fiber diet.

Ideal ratio diets

Some popular diets recommend that an “ideal” ratio—40 percent carbohydrates, 30 percent protein, and 30 percent fat—be consumed at every meal. This proportion supposedly creates the best ratio of insulin and glucagons, two hormones that work in opposition to regulate blood sugar levels. Emphasis is placed on the “glycemic index” (GI) of foods. The GI ranks carbohydrates based on their immediate effect on blood glucose levels. Carbohydrates that break down the fastest—white potatoes, rice and breads, refined foods, candy bars—have a high GI. This diet encourages low-GIfoods—whole grains like brown rice, barley, and oats, as well as raw vegetables—to keep you feeling satisfied longer and provide lasting energy to prolong physical endurance.
 
Does it work? This diet works, too. Diets based on ratios lead people to choose carbohydrates that are more nutritious per calorie, and the diet generally has sufficient fiber. It can be complicated to analyze the ratio of each meal, though “40-30-30” prepared foods can be purchased. The consumption of higher amounts of protein than generally are considered healthy might be of concern, but there is no long-term information or scientific study about this diet.

Group support diets

While the preceding diets might be termed “self-help” diets, there are group-support weight management systems available as well. One of the oldest, Weight Watchers, has expanded from its traditional weekly meeting schedule to include an Internet-based support system. Its Web site offers information, recipes, participatory forums, and inspiring stories. Some online sections are available to program subscribers only.

A weekly point system is established based on the person’s present and target weights. Points are assessed for specific portions and kinds of food. Activity points for various types of exercise offset food points or increased weight loss. Subscribers may keep track of their points online.

Does it work? This system can be an effective weight-loss plan. Followers find the face-to-face support and guidance motivating, and the online support also is a positive reinforcement. Food consumption is seen as only one part of long-term weight management, with emphasis placed on healthy lifestyle choices and exercise. A wide selection of branded food items is available. Many followers find it easy to stick with this plan for the long term.

Which diet is best?

The results of a head-to-head trial of four types of weight-loss plans were announced this past November at the American Heart Association’s annual meeting. Conducted by Tufts University researchers, the study showed that, regardless of the plan followed, those who stuck with their specific diet for a year lost an average of 5 percent of their body weight—about 10 pounds for a 200-pound person.
 
While no single weight management approach was found to be particularly more effective, all regimens produced significant improvements in lowering the risk of heart disease, even if weight loss was not significant.

“Initially, when people are motivated, if you pay attention to what you’re eating and follow the rules, you’ll
lose weight,” says Dr. Meir J. Stampfer, professor of epidemiology and nutrition at the Harvard School of Public Health.

What is more important than a specific diet regimen, says Stampfer, is to think about the composition of your diet. “The issue,” he continues, “is how to come up with a satisfying diet that tastes good, is balanced with reasonable amounts of fat and protein and low on refined [carbohydrates], and that people will follow for life.”

A good route to this perfect diet is to follow a food pyramid. There are two new pyramids to consider:

Harvard’s Healthy Eating Pyramid

The Healthy Eating Pyramid, developed by Stampfer and Dr. Walter C. Willett, a Harvard professor of epidemiology and nutrition, encourages eating healthy unsaturated fats at most meals and emphasizing plant oils, such as canola or olive. Whole grain foods also are recommended at most meals. Refined carbohydrates such as white rice, white bread, or pasta, and foods with saturated fats such as red meat, butter, and dairy products should be consumed sparingly. A daily multivitamin is recommended, as is moderate consumption of alcoholic beverages.

Unlike other food pyramids, this pyramid includes daily exercise and weight control. “It’s very hard to maintain ideal body weight without exercise,” says Stampfer.

The 70+ Pyramid

Nutrition for the aging person is a major focus for researchers at the Jean Meyer usda Nutrition Research Center on Aging at Tufts University in Boston. A result of one of their recent studies is a slightly narrower and taller version of the familiar usda food pyramid. “The change in dimensions [is to] encourage eating more fruits, vegetables, and low-fat dairy products foods above a smaller cereal and grain base,” explains Helen Rasmussen, a researcher at the center. “This diet plan is well-rounded and nutrient-dense. It could well be started at 50 rather than 70, and it also works well if you are eating fewer calories to lose weight.”

At the top of the pyramid appears a little icon labeled calcium, vitamin d, and vitamin b-12. These nutrients are hard to get in sufficient quantities strictly from food, and studies have shown them all to be particularly important to health.

The most noticeable change to this food pyramid is its foundation of eight servings of water. “Water is essential in that it carries nutrients and eliminates waste products in the body,” says Rasmussen. And, although recent research has indicated not everyone needs as much as eight glasses, water still is an important factor. Older adults often drink less fluids because of decreased thirst sensation or to avoid disturbing their sleep to use the bathroom. But, explains Rasmussen, “Having to pee often isn’t a
reason not to be hydrated—especially if you are taking medications.”

The bottom line

With so many options and opinions, what’s a beginning dieter to do? Weight management simply is the balance of calories eaten and calories burned. Ultimately, faithfully maintaining a weight-management system over the long term is more important than which particular diet you follow.

Remember all fats are not created equal, nor are all carbohydrates. Reading food labels carefully can help you avoid eating excessive saturated fats and trans-saturated fats and refined carbohydrates. Posting a food pyramid in your kitchen could serve as a visual reminder of a good diet to follow. If you stay faithful to your diet, your future could hold a healthier—and slimmer—you.