Diet Plan Buying Guide

Just be realistic. Your own expectations play a big role in how satisfied you’re likely to be with any diet you try. Let’s face it: Most people don’t have "Biggest Loser"-style outcomes. In our survey, only 14 percent of readers who’d finished their diets came to within 5 pounds of their goal weight. But take comfort in the fact that dropping as little as 5 to 10 percent of your starting weight can make a real difference in your health and well-being. If you have realistic goals, you’re likely to feel better with the weight you lose. And don’t give up if you don’t like the first plan you try. At least some readers found success on all of these diets.

For more, including a table that shows how much weight readers lost, see our article Lose Weight Your Way.

Atkins Diet
Best for: People who love the idea of a diet that lets them eat bacon, steak, and full-fat mayonnaise. How it works. By eating next to no carbs at first, our bodies are forced to burn fat instead. As weight loss progresses, more carbs are allowed. You eat foods such as meat and seafood, fats and oils, some non-starchy veggies and full-fat dairy, but no fruits or anything with added sugar. Learn how at atkins.com or in "The New Atkins for a New You," by Eric C. Westman, M.D., Stephen D. Phinney, M.D., and Jeff S. Volek, Ph.D. (Touchstone, 2010).

Glycemic Index Diet
Best for: People who can’t bear to give up all carbs but are willing to forgo some. How it works. The Glycemic Index (GI) indicates how fast your blood sugar might go up after you eat something with carbs in it. Lower is better. Potatoes and refined grains have a high GI. Whole grains, beans, and most fruits and vegetables have a low one.

Jenny Craig
Best for: Dieters who hate cooking and have trouble with portion control. How it works. You eat Jenny’s branded meals and snacks, plus buy your own produce, and get personal counseling in a walk-in center or by phone. Get the scoop at jennycraig.com.

Low-Carb Diet (other than Atkins)
Best for: People who don’t want to go on Atkins but think they can do well with fewer carbs. How it works. We’re not sure, frankly, what dieters ate--except that it was presumably low in carbs such as rice and pasta and was not the Atkins Diet.

Medifast
Best for: People who want to lose a lot in a hurry. How it works. Most dieters start at a low, low 800 to 1,000 daily calories, eating five low-fat, low-sodium prepackaged meals, plus one "lean and green" meal (5 to 7 ounces of lean protein and some veggies). You can also choose from optional snacks. Learn more at medifast1.com.

Mediterranean Diet
Best for: People who like Mediterranean cuisines. How it works. You eat like a Greek, Italian, or Spanish peasant: plenty of vegetables, fruits, nuts, legumes, and fish; a small amount of meat; and olive oil galore. There’s not much dairy except for yogurt and a bit of cheese, and very few sweets. You can get information online (oldwayspt.org is a good place to start) and in numerous books.

MyFitnessPal
Best for: People who want an easy way of keeping a food diary that provides a running total of calories. How it works. It’s a calorie and exercise tracker you can access on a free smart-phone app and at myfitnesspal.com. The two sync with each other, and the app is free for Android, Apple, BlackBerry, and Windows phones (search app markets for "My Fitness Pal"). You input what you eat and when you exercise; the more you move, the more calories you get!

Nutrisystem
Best for: Noncooks who want to spend the least possible money on packaged foods. How it works. It’s all about portion control. You eat branded entrées and desserts, and low-glycemic sides and snacks that you buy based on an approved list. Learn more and order at nutrisystem.com.

Paleo Diet
Best for: Carnivores who couldn’t care less about dessert. How it works. The idea is that we are genetically programmed to eat like our cavemen ancestors did, so we should follow their diet. That means lots of lean meat and seafood, fresh fruits, berries, and nonstarchy vegetables, but no dairy, cereal grains, legumes, processed foods, or refined sugar. Get information at thepaleodiet.com or in "The Paleo Diet," by Loren Cordain, Ph.D. (Wiley, 2010).

Slim-Fast
Best for: People who really, really, really don’t like to cook, or who have to eat on the go a lot. How it works. Technically it’s a meal-replacement plan, with snacks, shakes, bars, and some regular foods. But our dieters used the Slim-Fast foods more as part of a plan of their own devising, meaning they ate their own food sometimes and the Slim-Fast foods sometimes. You can buy the products in supermarkets, drugstores, mass retailers, and online.

South Beach Diet
Best for: Those who know their way around a kitchen--you’ll be cooking a lot. How it works. In the early phase you eat mostly lean protein, such as seafood, eggs, low-fat dairy, nuts, and high-fiber vegetables; later you add healthy carbs (whole grains, fruit--and wine!). Learn the ins and outs at southbeachdiet.com or in "The South Beach Diet," by Arthur Agatston, M.D. (St. Martin’s Griffin, 2005).

SparkPeople
Best for: People who like a mobile app and also appreciate guidance. How it works. You track your exercise and eating with the SparkPeople app (free for Android, Apple, and BlackBerry) and at sparkpeople.com. The two work interchangeably. If you want suggested menus and recipes, you can call up options for every meal (snacks too).

Weight Watchers
Best for: People who appreciate support. How it works. You try to stick within your PointsPlus quota, a proprietary formula that factors in a food’s protein, carbs, fat, and fiber. Fresh fruits and veggies count for zero Points. You get behavioral support at weekly meetings or help with online tools.