Table of Contents > Alternative Modalities > Slim-Fast DietŪ Print

Slim-Fast DietŪ


Also listed as: Diet, Slim-Fast
Related terms
Author information

Related Terms
  • Diet, eating plan, liquid meal replacements, meal replacements.

  • The Slim-FastŪ diet is an eating plan that aims to help people lose weight. The diet is based on consuming Slim-FastŪ portion- and calorie-controlled prepared foods while the individual learns the principles of healthy food selection and portion control. Slim-FastŪ diet products are integral to this eating plan, and they include shakes, nutrition bars, packaged meals, and other dietary supplements.
  • Slim-FastŪ products are sold in the United States, United Kingdom, Canada, France, Germany, Mexico, Brazil, and the Netherlands. The United States headquarters of Slim-FastŪ is in Englewood Cliffs, New Jersey. Slim-FastŪ has promoted its product line and diet using a variety of celebrities.
  • Slim-FastŪ was founded in 1977 as a part of the Thompson Medical Group. The founder made the company private in 1987, and it was acquired by the Anglo-Dutch corporation UnileverŪ in 2000. Soon after, Slim-FastŪ experienced severe profit losses due to the surge of popularity in low-carbohydrate diets, also known as low-carb diets. Slim-FastŪ was originally created to assist individuals in losing weight without focusing on adopting a healthy lifestyle. To expand its market appeal, however, Slim-FastŪ has recently diversified its product lines and approaches to dieting. Slim-FastŪ now offers diets that are designed for individuals whose primary motivation in losing weight may be for health-related reasons. For instance, people may choose to lose weight to lower their chances of developing diabetes or having a heart attack.
  • Though Slim-FastŪ used to advocate consuming two of its shakes and a "sensible dinner" every day, the diet is now less rigid, and offers more personalized eating recommendations that may allow for more options than the original meal plan. Today, there are five types of Slim-FastŪ products available for purchase. These include Original, Optima, Low-Carb, High Protein, and Easy-to-Digest. These Slim-Fast products are known as "meal replacements," because they provide a fair amount of nutritional value while remaining low in calories.
  • The Slim-FastŪ Corporation cites more than 35 published clinical studies, which it claims provide strong evidence that the diet will help individuals lose weight. Although many of the trials used prepared drinks called meal replacements, none of the studies used Slim-FastŪ brand products. Also, the quality of these studies varies. Furthermore, some of the studies have focused on the reduction of a person's likelihood of developing a disease, rather than weight loss. The use of meal replacements has been studied as a tool in examining the likelihood of developing osteoarthritis, heart disease, and type two diabetes. The American Dietetic Association endorses the consumption of one or two meal replacements, which it defines as pre-packaged meals, liquid meals, and low-calorie bars for individuals who may have difficulty selecting healthy foods or exercising portion control. The American Diabetes Association endorses meal replacements as a potential resource for weight loss. However, neither of these organizations exclusively endorses Slim-FastŪ products as the meal replacement used for these purposes. Meal replacements similar to the ones marketed by Slim-FastŪ are available from a variety of companies. Most major clinical trials have found that a person's ability to follow a diet plan, regardless of its meal structure, over the long term is the most important factor in determining the likelihood of a patient's dieting success.
  • Slim-FastŪ products have recently been marketed in conjunction to the Best Life Diet. "The Best Life Diet" is a book published in 2006 by exercise physiologist and certified personal trainer Bob Greene. The book instructs readers on a weight loss method devised by Greene that focuses on eating rituals and the modification of eating behavior over time. The diet does not purport to offer an immediate solution to the eating patterns of readers; rather, Greene encourages readers to examine their motivations for eating and gradually change their lifestyle in three phases. The popular television celebrity Oprah used this diet to lose weight and wrote the introduction to Greene's book. Before actually beginning the diet, individuals analyze their psychological associations with food, eating, and weight loss. This analysis hopes to address the emotional reasons underlying an individual's perceived weight problem, the motivation to lose weight, and the reasons why the individual has not been able to maintain weight loss in the past. The author contends that readers who are not fully aware of their motivations for and associations with eating will most likely not succeed in the diet because unexamined emotions may alter the effects of the diet.

Theory / Evidence
  • The Slim-FastŪ diet is created around the premise that controlling hunger is one of the most difficult issues of following a new eating plan to lose weight. The Slim-FastŪ corporation claims that its products retain a sensation of fullness for up to four hours. This sensation of fullness may prevent the people who consume these products from eating more, because they will not feel hungry.
  • The Slim-FastŪ corporation claims that its products help people become healthier by promoting food portion control and informed selection of foods.
  • A 2006 study by Truby et al. evaluated four popular diets, including Slim-FastŪ, and found that all patients lost about the same amount of weight when assigned to one of four diets for a period of six months. Following the diet plan for the length of the trial was the most important factor in patient weight loss.
  • A 2004 study by Huerta et al. provided Slim-FastŪ products to lower income obese patients. All patients were instructed to consume one low calorie meal a day, in addition to two Slim-FastŪ meal replacements a day. Patients who adhered to the diet reached an average of 7% reduction in body weight, and the study authors suggested that meal replacement products be incorporated into nutrition clinics serving lower income patients.


Author information
  • This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (

  1. Centers for Disease Control and Prevention (CDC). .
  2. Early JL, Apovian CM, Aronne LJ, et al. Sibutramine plus meal replacement therapy for body weight loss and maintenance in obese patients. Obesity (Silver Spring). 2007 Jun;15(6):1464-72.
  3. Huerta S, Li Z, Li HC, et al. Feasibility of a partial meal replacement plan for weight loss in low-income patients. Int J Obes Relat Metab Disord. 2004 Dec;28(12):1575-9..
  4. Noakes M, Foster PR, Keogh JB, et al. Meal replacements are as effective as structured weight-loss diets for treating obesity in adults with features of metabolic syndrome. J Nutr. 2004 Aug;134(8):1894-9.
  5. Slim-Fast. .
  6. Truby H, Baic S, deLooy A, et al. Randomised controlled trial of four commercial weight loss programmes in the UK: initial findings from the BBC "diet trials". BMJ. 2006 Jun 3;332(7553):1309-14.
  7. Yang GH, Ma JM, Liu N, et al. [Study on diet, physical activities and body mass index in Chinese population in 2002] Zhonghua Liu Xing Bing Xue Za Zhi. 2005 Apr;26(4):246-51.
  8. Yip I, Go VL, DeShields S, et al. Liquid meal replacements and glycemic control in obese type 2 diabetes patients. Obes Res. 2001 Nov;9 Suppl 4:341S-347S.

  • The foundation of the Slim-FastŪ Diet is the use of its products as meal replacements. Bars, shakes from powders, and pre-mixed drinks are some of the products available to consume in lieu of a more conventional meal.
  • Slim-FastŪ products are sometimes consumed as snacks or as part of a meal. For example, a 200 calorie Slim-FastŪ protein bar may be eaten between meals. In other instances, a Slim-FastŪ product may be consumed with an additional 200 calories as a meal, such as a Slim-FastŪ bar eaten with a mini pizza containing fewer than 15 grams of fat for lunch, or a Slim-FastŪ shake eaten with half of a turkey sandwich for dinner.
  • The Slim-FastŪ diet encourages a regimen of what it called the "Sensible Meal Guide." This guide is used for meals that are not made up of Slim-FastŪ products. In general, half of a plate should be filled with vegetables, such as green beans, carrots, cauliflower, cabbage, eggplant, spinach, peas, broccoli, asparagus, peppers, mushrooms, or squash. This is usually about half a cup of cooked vegetables, or one cup of uncooked vegetables. One fourth of the plate should be filled with protein, such as lean beef, pork, poultry, fish, eggs, low fat dairy products, tofu, and meat replacements (such as soy meat). The protein portion should be about the size of a deck of cards. The final fourth of the plate should be comprised of starches, such as potatoes, corn, pasta, noodles, rice, or whole wheat bread. One small baked potato, half a cup of whole wheat pasta, one third cup of brown rice, one slice of whole wheat bread, or one small multigrain roll are examples of portion sizes. A side dish of one cup of a tossed salad or a dish of fruit along with a calorie free beverage is also acceptable.
  • The Slim-FastŪ diet provides emotional support to individuals in the form of phone trees, webpages, and customer representatives. The company also retains a staff of dieticians should consumers require a consultation.
  • The Slim-FastŪ diet makes a variety of online resources available to its customers to assist in achieving weight loss. These resources discuss determining portion sizes, reading food labels, understanding liquid calories, coping with food cravings, creating shopping lists, tracking weight changes, and spicing foods. The website also features guides for dining out, finding healthy convenience store foods, and making healthier selections at fast food restaurants. Recipes that follow the Slim-FastŪ diet regimen are also available on the site.
  • Regardless of how online tools are used or foods are consumed, the Slim-FastŪ diet suggests that people eat the equivalent of two of its products as meal replacements every day over an extended period of time to achieve weight loss.
  • Slim-FastŪ products are available in five dieting style varieties: Original, Low-Carb, High Protein, Optima, and Easy-to-Digest. For each of these varieties, Slim-FastŪ sells a variety of canned drinks, powdered drinks, meal bars, and snack bar foods.
  • The Original Slim-FastŪ products are designed for those without special dietary needs. The Low-Carb products contain fewer carbohydrates than the Original variety, and are designed for individuals who plan to reduce their consumption of carbohydrates in order to lose weight. The High Protein products supposedly boost the metabolism, and may be appropriate for athletes. The Optima products contain added protein and vegetable fat to help an individual retain a greater feeling of fullness than the Original products. Finally, the Easy-to-Digest products are lactose- and gluten-free, and designed for individuals who experience gastrointestinal upset after consuming these substances.

Copyright Đ 2011 Natural Standard (

The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.

Search Site