by Julia Blank, MD
So you’re driving down Wilshire, past the familiar tract of fast-food joints, and suddenly you do a double-take. Was that Burger King offering a low-carb menu? And was that a Subway sign touting Atkins-friendly wraps alongside its 6-grams-of-fat sandwiches?
Everywhere you go, low-carb is all the rage: lettuce-wrap burgers at McDonald’s, low-carb chips at the deli, carb-controlled candy bars at the supermarket check-out, the South Beach Diet and Dr. Atkins Diet Revolution on the bookstore shelf.
What ever happened to “low fat”? Despite the bad rap that low fat diets have recently gotten in the press, low-fat/reduced-fat/fat-free products are still available—and, it seems, as popular as ever.
With so many foods and diets to choose from, how do you decide what to eat? And what is the best approach to weight loss—and maintenance of healthy weight?
A Weighty Problem
If you’re concerned about your weight, you’re not alone: studies suggest that at any given time, up to 44% of Americans are trying to lose weight. In the process, they spend $40 to $60 Billion dollars a year on everything from diet drinks and health club memberships to diet books and commercial weight loss programs.
Despite this, the number of overweight and obese Americans continues to climb. According to the latest National Health and Nutrition Examination Survey (NHANES III), 64.5% of American adults are overweight—up from 46% two decades ago. Of overweight adults, 30.5% are considered clinically obese (i.e. BMI of 30 or more), up from 14.4% in 1980.
The problem with excess weight is that it leads to significant health complications such as diabetes, high blood pressure, elevated cholesterol, heart disease, arthritis, and some forms of cancer. Obesity increases overall risk of death from all causes by 50-100%. In other words, obesity can shave off an estimated 2-5 years of life expectancy. The health problems associated with obesity are also responsible for a significant increase in healthcare costs. For example, 2001 healthcare costs for diabetes associated with excess weight rose to $98 Billion.
Even more alarming, the percentage of children who are overweight and obese continues to rise as well. Between 1980 and 2001, the percentage of overweight and obese children doubled to 20%. Studies show that children who are overweight tend to grow into adults who are overweight; they also develop obesity-related health complications at earlier ages.
Dietary Trends
Several factors have contributed to the “fattening of America”. Portion sizes have doubled and tripled over the last few decades, resulting in a tremendous increase in daily caloric intake in the American diet. You see this trend everywhere: from the oversized bagels and muffins on sale at your local Starbucks, to the double-sized burgers and fries at every fast-food dive, to the family-size entrees at the chain restaurant down the street.
Even our advertising reflects this trend: remember the television commercial for the all-you-can-eat buffet, featuring a satisfied customer who says, “I ate a lot, but I sure didn’t pay a lot”?! Unfortunately, more food for your dollar isn’t necessarily the best choice for your health.
At the same time that our food portions have been increasing, our physical activity has been declining. We have become a sedentary culture. We go from car to desk to car to couch, with fewer than 33% of American adults getting the minimum recommended amount of physical activity on a routine basis (i.e. 30-60 minutes of light or moderate physical activity 5 times or more per week). Forty percent of American adults do not do any leisure-time physical activity at all!
So, we eat more than ever, and exercise less than ever. Any wonder, then, that we continue to gain weight?
The solution seems obvious: limit portion size, and increase exercise. So why are so many of us still struggling? And why are we still chasing after a quick fix?
There is no end to fad diets (remember the grapefruit diet, the cabbage diet, the “Think Yourself Thin” diet?), mostly because there is no end to the demand for something structured that “guarantees” weight loss. The problem is that no matter how we lose the weight, once we go off the diet—as we inevitably do, since few diets are realistically sustainable in the long-run—we regain the lost weight and more.
This raises the following question: what is a “healthy diet”, and how can it help us to lose weight and/or successfully maintain a healthy weight?
The Low-Fat Solution
Traditionally, the recommended diet has been a low-fat, calorie-controlled diet based on the now-familiar food pyramid. With this diet, carbohydrates provide 55-65% of total calories, protein provides 15%, and fat provides up to 30%.
Many formal diet programs, such as Weight Watchers, Jenny Craig, and Nutrisystem are based on this approach. Likewise, this dietary break-down provides the basis for the “Step I” and “Step II” diets recommended by the American Heart Association for patients with heart disease and high cholesterol.
The problem with the “low-fat” approach is that it is too often applied without an appropriate—and necessary—element of common sense. “Low-fat” does not mean “calorie-free” (if you read the fine print on many low-fat, fat-free, and sugar-free products, you’ll find the following statement: “not intended for weight control”). The flood of low-fat and fat-free products on the market have unfortunately also given free reign to guilt-free over-consumption of these foods, leading to even greater weight gain. (See “Are the Low-Fat Foods Making You Fat?”)
Anecdotal evidence and resulting media hype regarding other dietary approaches have challenged conventional wisdom regarding the low-fat approach. The Mediterranean diet, for example, advocates a higher proportion of fat in the diet (mainly from “heart-healthy” mono-unsaturated fats, like those found in olive oil). While people who live in the Mediterranean and follow this diet have traditionally had a lower incidence of heart disease, it is not yet clear whether the diet alone is responsible: factors such as higher levels of physical activity may also play a significant role. To date, no long-term clinical studies have been conducted evaluating the health consequences of the Mediterranean diet.
The Low-Carb Solution
A more recent popular phenomenon has been the low-carbohydrate high-protein diet. Examples of this diet include:
The controversy over low-carb diets was heightened in 2003 with the publication of two studies in the New England Journal of Medicine, comparing low-carbohydrate versus low-fat diets. The studies were small (63 and 132 patients), with high drop-out rates for both low-carb and low-fat groups (about 40%). The studies were also short-term, following patients for 6 months in one study, and 12 months in the other. The results showed greater weight loss at 6 months in the low-carb group, though weight gain in both groups by 12 months resulted in a smaller (though still statistically significant) difference favoring the low-carb group. The low-carb group also had greater reduction in triglyceride levels and fasting blood sugar (a marker for diabetes). There were no significant or consistent differences in other parameters such as total cholesterol, LDL, HDL, and blood pressure. (For a summary on cholesterol, LDL, HDL, and triglycerides, see “Cholesterol: the Good, the Bad, and the Ugly”)
Critics of these studies argue that weight loss in the low-carb group resulted from greater caloric restriction. This may be because low-carbohydrate/high-protein diets induce a metabolic state called “ketosis,” which leads to appetite suppression (as well as higher stress on the kidneys and bad breath).
Still, these results call into question long-held conventional wisdom regarding the health benefits and efficacy of low-fat diets, as well the potential risks of low-carb diets. However, because of the small size, high attrition rates, and short follow-up, the results should also be interpreted with caution. More long-term data is needed before any conclusion can be made regarding low-fat versus low-carb diets.
One thing, though, is for sure: both studies underscored how difficult it is to stick with any diet.
Getting It Off and Keeping It Off: the Bottom Line
The National Weight Loss Registry is an ongoing database of over 3,200 people who have lost 30 pounds or more and successfully maintained the weight loss for at least a year. How did they do it? The following are some of the lessons learned from these “success stories”:
Of course, there are exceptions. Some people who are clinically obese and have obesity-associated health conditions such as high blood pressure, high cholesterol, and diabetes may benefit from medication to help them lose weight (e.g. Orlistat™ and Meridia™). Some people who have 100 or more pounds to lose may even benefit from surgical treatment (see “gastric bypass” and “LAP-BAND®”). There is also ongoing research into hormonal, metabolic, genetic, and other factors contributing to obesity, with potential implications and product development for weight management.
In the meantime, however, most of us need to rely on common sense and moderation.
Whether you choose the low-fat or the low-carb route, or something in between, remember the following: