Slim Fast Diet

What is the Slim Fast Diet?

The Slim Fast Diet is a weight loss diet that uses low calorie meal substitutes as replacements for some of your meals. This very structured diet controls portions, fats, and starches and includes physical activity and support – all of which combine to support you in losing weight.

Although calories are limited to about 1,200 per day, there is no calorie counting with the Slim Fast Diet. You eat six small meals or snacks every day, using Slim-Fast meal replacement foods for two meals and one snack each day. You supplement the Slim-Fast foods with lean proteins, fruits, and vegetables. While the diet is highly structured to keep you on track, you do have some options about the foods you eat. No foods are prohibited outright. Alcohol consumption is discouraged, but not banned.

In 2009, Slim-Fast launched its 3-2-1 diet plan. In this simplified plan, you eat 3 100-calorie snacks, 2 200-calorie meal replacements, and 1 500-calorie (600-calorie in the United Kingdom) dinner. Slim-Fast pre-packaged foods include snacks and meal replacements. You are on your own for dinner; frozen dinners are popular and convenient choices for Slim-Fast dieters, and eating out is okay as long as you eat sensibly. Slim-Fast recommends a sensible dinner consisting of half a plateful of vegetables and a quarter-plateful each of lean protein and whole grains.

The Slim-Fast snack bars, which come in five different flavors, have 100 calories each. The 180-200-calorie Slim-Fast meal replacement shakes come either ready to drink or as a powder to be mixed with milk. There are eight flavors of shakes, including lower-carb and higher-protein shakes. Slim-Fast meal replacement bars have 200 calories each and come in six different flavors. The meal replacement products (shakes and bars) are fortified with vitamins and minerals, but the snack bars are not. You have to like the Slim-Fast products to stay on this diet.

The Slim-Fast Diet is designed to help you lose 10 percent of your body weight in six months, or about one to two pounds per week. You can expect to start losing weight by the end of the first week. Slim-Fast is well suited to people who want to lose about 20 pounds, which they can do in eight to ten weeks. Many dieters use Slim-Fast replacement meals occasionally to help them maintain their weight loss after they complete the diet.

You can buy Slim-Fast products online through and or at most grocery stores. Snack bars cost about $2.00 each or 24 for under $20.00. A pack of 24 ready-to-drink shakes costs about $35.00.

How the Slim-Fast Diet Works

With Slim-Fast’s trademark 3-2-1 plan, you eat 3 snacks, 2 Slim-Fast shakes or meal bars, and 1 dinner each day. In addition to–or instead of–Slim-Fast snack bars, you can eat other healthy snacks such as nuts (almonds or walnuts), fruit (melons, berries, grapes, bananas, apples), and vegetables (carrots, broccoli, celery, tomatoes, bell peppers). Half a banana or a whole pear is equivalent to one snack bar. And drink plenty of water.

You can use the Slim-Fast website to track your physical activity and weight, create a personal meal plan, and get support from other dieters. A registered dietitian is available online to answer questions.

Slim-Fast recommends that you weigh yourself once a week—with the same scale, on the same day, and at about the same time each week—and record it on your Slim-Fast weight chart.

Exercise is important in the Slim-Fast Diet: Thirty minutes a day at least five days a week, but it doesn’t have to be a vigorous workout.

Benefits of the Slim-Fast Diet

Slim-Fast provides calorie-controlled portions, so dieters do not have to concern themselves with planning meals and determining appropriate portion sizes. The prepackaged foods also make Slim-Fast an easy and convenient diet to follow.

The Slim-Fast diet provides enough vitamins, minerals, and other nutrients for the average adult. Supplements are typically not needed.

The Slim-Fast Diet encourages exercise and provides customizable online support.

At one to two pounds per week, the rate of weight loss is slow and gradual, which is generally a better and more sustainable approach than rapid weight loss.

The Slim-Fast Diet conforms to the 2010 Dietary Guidelines for Americans.

No serious side effects or health risks are associated with this diet. Three studies show that many people with diabetes who followed the Slim-Fast Diet were able to reduce their diabetes medications.

Concerns about the Slim-Fast Diet

Some dieters report side effects such as headaches, intense hunger, gas, constipation, and abdominal pain—side effects common to many low calorie diets. Such side effects typically do not last long.  Headaches may be the result of the artificial sweetener aspartame in the products. The health risks of aspartame are subject to debate.

Slim-Fast does not teach people how to plan and prepare healthy meals. As a result, people who follow the diet may go back to their regular diets and regain the weight they lost—and more.

The calorie-restricted Slim-Fast diet may not provide enough nutrients for people who are very active physically.

The diet is not designed for people under 18 years old or for pregnant or nursing women.

Is the Slim-Fast Diet for You?

The Slim-Fast Diet is a moderate calorie-controlled diet for slow and steady weight loss. If you have a chronic medical condition, are on medications, or have obesity-related health issues it is important to discuss your diet plans with your healthcare provider before starting any new weight loss or exercise plan. The same is true for children, pregnant women, and nursing mothers.