Which Diet Is Best?

The first of a 5-part series on figuring out which diet is best for you.

Monica Reinagel, MS, LD/N, CNS
5-minute read
Episode #75

It’s that time of year when everyone starts making their New Year’s resolutions. A lot of those resolutions will have to do with diet: many people resolve to lose weight; others may simply resolve to eat healthier. But if you’re in the market for a new diet plan, you’ll soon discover that there are hundreds to choose from.

Which Diet Works Best?

Everyone seems to agree that January 1 is a good time to start eating healthier. But what is the healthiest diet? Well, there, the agreement ends—especially when it comes to weight loss.

Some people insist that low-carb is the only way to go. According to this crowd, not only do low-fat diets not work—they actually make you gain weight. Others insist that it’s not realistic to make whole categories of food off-limits and that the sane approach to weight loss is simply training yourself to eat a little bit less of everything. Then there are the folks who say that if you want to be healthy and lose weight, you just need to eat like the Greeks, or the Eskimos, or the Japanese, or the Neanderthals.

But it Worked For Me!

Once people have embraced a particular dietary theory, they can get extremely passionate about it. Perhaps they’ve successfully lost weight, or reduced their cholesterol, or gotten off their diabetes medications. In their minds, this constitutes scientific proof that their dietary philosophy is right. People have a tendency to believe that what worked for them is the only thing that works—and that it will work equally well for everyone. (This is especially true once there is a book contract involved.)

But for every low-carb crusader, there’s a low-fat fanatic, a high-protein prophet, a South Beach supporter, an Atkins advocate, a pyramid promoter, a Zone zealot, a mindful eating maven and somebody else counting up Weight Watcher’s points—all of them LIVING PROOF that their method is the one true path to healthy weight loss. They can’t all be right. So, what does the research have to say?

Well, no matter what side you want to argue in this debate, there is plenty of research to support your position. There are lots of studies comparing low-carb and low-fat diets, for example. Some find that low-carb diets are more effective. Others find that low-fat diets are more effective. Some find that people following Mediterranean diets lose more weight.

Do Diets Work?

But when you back up and consider the entire body of evidence, it turns out that all these different diets are all equally effective. Actually, I think it might it’s more accurate to say that they are equally ineffective. Regardless of what diet you’re talking about, the vast majority of people fail to lose weight or, if they achieve a healthy weight, they fail to maintain it.

I just read a paper in the New England Journal of Medicine that reviewed much of the recent research on this, including a new study which sought to “answer the impact of dietary composition on weight loss…once and for all.”

They recruited almost a thousand overweight people and randomly assigned them to diets with varying levels of protein, fats, and carbohydrates.  After two years, there were no differences in weight loss between the groups. All groups also had the same scores in terms of hunger and satisfaction. The researchers concluded that dietary composition has no impact on weight loss. But here’s what stuck out to me: Only 15% of the dieters managed to lose a meaningful amount of weight.

Do Genetics Cause Obesity?

Maybe the reason that these success numbers are so low is that the subjects were randomly assigned to the various diets. We don’t all respond the same way to the same diets. Some of these differences are genetic. For example, geneticists have isolated what they call an obesity gene. If you have this gene, you are two and half more times to be obese than someone without this gene. But if you have this gene and you follow a low-fat diet, you have the same risk of obesity as someone without that gene.

Which Diet is Right for You?

You want a weight-loss strategy that doesn’t require you to eat stuff you don’t like, and that doesn’t leave you feeling hungry, sleepy, or grouchy.

One day you may be able to run down to the drug store and pick up a genetic screening test that will reveal to you the dietary prescription best suited to your genetic make-up. (Wouldn’t that be cool?) But genetics isn’t the only factor. Lifestyle, medical history, and preferences also play a role. If you’re an athlete, for example, you may thrive on a higher carbohydrate diet.  If you have high triglycerides or diabetes, a lower-carbohydrate diet may make more sense. If you’re a committed vegan, a high-protein diet probably isn’t the way to go.

There are a variety of ways to build a healthful diet. The real trick is to figure out which formula gives you the best chance of long-term success. You want a strategy that fits your lifestyle, that doesn’t require you to eat stuff you don’t like or forgo all the stuff you do like, that doesn’t monopolize all your time and mental energy, that doesn’t leave you feeling hungry, sleepy, or grouchy, and that produces the best results in terms of helping you manage your weight and health conditions. The answer is not going to be the same for everyone, and in a future episode I'll go over how to create your own best diet.

The Nutrition Diva’s Great Diet Experiment

Starting next week, I’m going to do a series of shows examining some predominant but conflicting diet theories. Most of today’s hot diet theories can be sorted into three broad approaches—the metabolic, the behavioral, and the epidemiological. I’ll do a show on each one, outlining the theory, the evidence, and some of the pros and cons. And then, each week, I’ll invite you to join me in a one-week experiment. We’ll implement some of the key principles of each approach for a week and then compare notes.

Whether your goal is to lose weight, avoid weight gain, or simply to improve the nutritional quality and balance of your diet by the end of January, I think you’ll have some valuable information about what dietary strategy is mostly likely to work for you.

I’d love to see a study that went through this exercise before assigning people to dietary regimens—and then evaluated the success rates of various diets. I bet the overall success rates would go up. I’d also be curious to what percentage of people would match themselves up with the various dietary strategies, and how the success rates of individual diets compare when you do a little match-making first.

Next week, I’m going to start with what I call the “metabolic” diet theories. Very broadly, these are the ones that argue that some foods are more likely to lead to weight gain than others and that you can eat as much as you want as long as you limit yourself to the “right” foods. If you’d like to get a head-start on next week’s discussion, pick up a copy of Good Calories, Bad Calories, by Gary Taubes.

Keep in Touch

If you have questions or comments about today’s show, you can post them below. Or, come join the discussion on the Nutrition Diva Facebook Page.   Also, there are lots more quick tips, recipes, and answers to listener questions in my free weekly newsletter, so be sure you’re signed up to receive that.

Have a great week and remember to eat something good for me!


Weight Loss Does Not Differ by Fat, Protein, or Carbohydrate Composition

Good Calories, Bad Calories, by Gary Taubes

Mindless Eating, by Brian Wansink


About the Author

Monica Reinagel, MS, LD/N, CNS

Monica Reinagel is a board-certified licensed nutritionist, author, and the creator of one of iTunes' most highly ranked health and fitness podcasts. Her advice is regularly featured on the TODAY show, Dr. Oz, NPR, and in the nation's leading newspapers, magazines, and websites. Do you have a nutrition question? Call the Nutrition Diva listener line at 443-961-6206. Your question could be featured on the show.