The Truth About Which Diets Work the Best

Diets. They’re what everyone buys and tries when they want to lose weight.

Atkins. South Beach. Paleo. The Zone. Raw food. Weight Watchers. Jenny Craig. (Insert your favorite diet here.)

Do you follow a diet? If so, don’t feel too defensive just yet. Diets serve a purpose: they give us structure and guidance when we’re trying to lose weight. Diets do have value.

But does one particular diet work better than the others, as the expensive marketing campaigns claim? Do low-carb, high-protein, or other combinations of macronutrients work better than another? And no one talks much about which diet is best for keeping the weight off – is any one diet more effective than the other in the long term?

A Study of Four Popular Diets

In a 2005 study reported in the Journal of the American Medical Association, 160 overweight/obese subjects were assigned to four diet types, which they followed for two years: Atkins, Ornish, Weight Watchers, and Zone. Most subjects did lose weight using one of the four diets and their risk of heart disease decreased as a result (cholesterol, CRP and insulin levels) [1].

While the Atkins dieters experienced a slightly higher rate of weight loss and adherence one year later, there was not a statistically significant difference among the diets’ weight loss results. (In addition, the long-term effects of a low-carb/high-protein diet are not yet clear.) And mirroring  real life, subjects in all four groups fell off their diet rapidly within four to 12 months of losing the weight, so most subjects regained some or all of the weight.

Does Adjusting Your Macros Work?

Manipulating the macronutrient composition of one’s diet – that is, how many grams of fat, protein, and carbohydrates you eat per day – has become a very popular way to sell diets. As we saw in the study above, the high-protein/low-carb Atkins diet did produce slightly better results. 

However, in a 2009 study conducted at the Harvard School of Public Health and Pennington Biomedical Research Center, a 24-month weight loss program compared the results of diets with different macronutrient compositions. The researchers studied 811 highly motivated, highly educated, and carefully selected participants who were given meal plans and exercise programs over a two-year period. After being given diets low or high in fat, average or high in protein, or low or high in carbs, the subjects had no appreciable difference in weight loss [2]. Satiety, hunger, and satisfaction were similar for all diets. The authors concluded that tailoring a diet based on personal and cultural preferences have the best chance for long-term success, and if that means differing amounts of macros, then that’s perfectly fine.

Keeping the Weight Off

Adherence to diets goes down over time for all types of diets. What does this mean? It doesn’t matter which type of diet you choose for weight loss, it’s difficult to maintain that weight loss using a diet.

Dr. Holly Wyatt, physician and clinical researcher at the Center for Human Nutrition at the University of Colorado Denver, says maintaining weight loss is primarily about exercise; most people simply cannot continue a restrictive diet in the long term. “Many people need to do more than 300 minutes of moderate-intensity activity a week to meet weight-control goals,” she says, while continuing a healthy diet within their recommended daily calorie intake. It should be noted that in adolescents, a recent study showed that increased activity is the answer to weight loss, not calorie restriction [3].

The Bottom Line

When it comes to weight loss, it always comes down to a negative energy balance, no matter what diet you use. Dr. Wyatt, summed it up nicely in her presentation at the Fitness and Health Bloggers Conference I attended in June 2012:

• Calories and adherence are very important
• Macronutrients (type/source of calories) are less important
• Adherence to quantity of calories trumps quality of calories
• Structure is associated with better adherence and greater weight loss (that is, meal plans, portion control, grocery lists, etc.)
• Activity is always good (additive) but not required for weight loss success (essential for weight maintenance, however)

Despite their massive marketing campaigns, there is no one “best” diet – not even the ones celebrities follow or the one you may follow. What works is finding a calorie restriction diet that you’ll follow. Keeping the weight off then means learning how to eat within your daily recommended calorie intake while making exercise a part of every day.

Image Credits: All images courtesy of Holly Wyatt, M.D., Associate Professor of Medicine, Associate Director, Anschutz Health and Wellness Center, University of Colorado Denver, Denver, CO. “Current Evidence on Weight Loss and Weight Management: What Do We Really Know?” Presented at the Fitness and Health Bloggers Conference, Denver, CO, June 2012.