Fat Smash Diet


The fat smash diet is a 90-day, four-phase weight-loss program that is designed to “smash” bad habits and make permanent lifestyle changes in eating and physical activity.


Dr. Ian Smith, MD, developed the fat smash diet plan after he became weight-loss consultant and judge for the VH1 hit television program Celebrity Fit Club. The plan was originally designed for celebrities trying to lose weight on the show. Smith's bestselling book, The Fat Smash Diet: The Last Diet You'll Ever Need, was published in 2006. In April of 2007 Smith published the Extreme Fat Smash Diet, an alternative program for people wanting to lose weight in a short period of time.



According to Smith, the fat smash diet plan is designed to “rewire” the body and its relationship to food and physical activity. It is based on lifestyle changes that will enable people to maintain their weight once they have achieved their weight-loss goals. The aim of the plan is to eliminate bad habits and enjoy food without overindulging. The fat smash diet is very flexible and utilizes a wide variety of healthy everyday foods, with the emphasis on whole grains, fresh produce, lean meat, fish, poultry, and healthy fats. Smith's book includes more than 50 quick and simple recipes. Although the diet does not involve calorie counting, quantities are suggested as a guide for keeping portions small.

The major principles behind the fat smash diet plan are:

The rules for success on the fat smash diet are:

Before beginning the fat smash plan dieters are instructed to:

The pyramid

The fat smash diet is constructed as a pyramid, with each of the four phases building on the previous phases:

The fat smash diet is designed to allow for mistakes. Dieters who overindulge or eat a prohibited food can return to phase 1 for about a week and then pick up the diet at the phase where they left off.

Foods allowed during phase 1 include:

Foods prohibited during phase 1 include:

Canned foods should be rinsed thoroughly to remove excess salt.

Although phase 1 lasts only nine days, dieters can choose to stay with phase 1 for one to two extra weeks or longer.

PHASE 2—THE FOUNDATION. In phase 2 the quantity of food is increased slightly and exercise is increased to 10%–15% more than in phase 1, or 35 minutes five times per week. Weight lifting and other types of anaerobic exercise are not recommended during phase 2.

Foods added during phase 2 include:

PHASE 3—THE CONSTRUCTION. The four-week construction phase requires at least four meals per day. It adds protein and whole grains to the diet, allows for larger portions, and continues ample amounts of fruits and vegetables. Exercise levels are increased by another 25% to 45 minutes daily. Smith recommends exercising twice per day several days per week to boost metabolism.

Phase 3 allows:

PHASE 4—THE TEMPLE. Any and all foods are allowed during the maintenance phase 4, including:

Phase 4 includes one hour of moderate to intense exercise, including weight training, five times per week. If weight is regained, the dieter can return to phase 1 for about a week.

Extreme fat smash

Smith's extreme fat smash diet is an alternative to the fat smash diet for people who want to lose weight rapidly by raising their metabolism, with a goal of losing up to 12 lb. (5.4 kg) in the first three weeks. He writes: “Extreme fat smash is for people who are determined to reach what they might've considered unthinkable success in a weight-loss journey. The idea is simple: if you want big results, then you'll have to push yourself beyond the normal limits to attain them.”

Like the original fat smash, extreme fat smash utilizes healthy foods and relies on portion control—eating only to satisfy hunger, with the knowledge that another meal or snack will be coming soon. It differs from the fat smash in that it requires organizing the day around meals and exercise:

The book Extreme Fat Smash Diet includes:

The extreme fat smash diet consists of three one-week cycles:

Anaerobic exercise—
Brief, strength-based activity, such as sprinting or weight training, in which anaerobic (without oxygen) metabolism occurs in the muscles.
Body mass index—
BMI, a measure of body fat determined from the ratio of one's weight in kg to the square of one's height in meters; the BMI from weight in pounds and height in inches is determined from tables; an adult BMI of 25–29.9 is considered overweight, and 30 or above indicates obesity.
Detox; cleansing; to remove toxins or poisons from the body.
Roughage; a complex mixture found in plant foods that includes the carbohydrates, cellulose, hemicellulose, gum, mucilages, and pectins as well as lignin.
Glycemic index—
GI; a measure of the rate at which an ingested carbohydrate raises the glucose level in the blood.

At the end of the three weeks, the dieter has the option of repeating the three cycles to lose more weight or of entering the maintenance phase. The same cycle cannot be followed for two weeks in a row.

There is an extensive snack food list that includes:

Unlike the original fat smash, the cycles are adjusted for individual body types, dieting profiles, and weight-loss goals of 5 lb. (2.3 kg), 10 lb. (4.5 kg), or 15 lb. (7 kg) and up. For example, an active person who has healthy eating habits but still cannot lose weight should:



The extreme fat smash diet is for people who want to lose 10–25 lb. (4.5–11 kg) in a healthy manner in a short period of time and maintain the weight loss.


The fat smash diet is a healthy, well-balanced, and flexible plan. It is a sustainable diet that allows unlimited fruits and vegetables and relies on regular inexpensive foods. Its calorie control, via portion control, and emphasis on exercise should lead to weight loss. Smith claims that people can lose from 6–10 lb. (3–5 kg) during phase 1. He further claims that the fat smash diet:

Portion control is a key to the fat smash diet, and Smith claims that even people who eat unhealthy foods can lose 10–15 lb. (5–7 kg) in a year by practicing portion control—eating smaller meals that still satisfy hunger—without making any other changes.


The fat smash diet may be difficult for some people to adhere to, particularly during the nine-day detoxification phase. The weight loss in phase 1 is due to its severe calorie restriction. There is little allowance for occasional indulgences. Eating out is almost impossible during phases 1 and 2. The recipes in the book are sometimes inconsistent, with some phase 1 recipes containing prohibited ingredients.

The extreme fat smash may be too extreme and inflexible for many people.


The fat smash plan is a healthy, well-balanced diet that should have few health risks. The extreme fat smash diet may produce too rapid of a weight loss for some people.

Research and general acceptance


With its emphasis on fruits and vegetables, wholegrain foods, lean meats, portion control, and physical activity, the fat smash diet is considered to be scientifically sound. Tara Gidus of the Academy of Nutrition and Dietetics told AOL Diet & Fitness: “It helps people eat more low-calorie, nutrient dense foods, exercise more and get rid of unhealthy habits. I love that it encourages so much aerobic exercise.” Although the fat smash detox is relatively moderate, there is no scientific evidence to show a person can detoxify their body through diet.

Most research suggests that slow, gradual, and consistent weight loss is the healthiest way to lose weight and increases the likelihood of maintaining the weight loss.

General acceptance

Although The Fat Smash Diet earned mixed reviews among diet critics, Ian Smith enjoys a high degree of credibility among his audience. He is a Harvard-trained medical doctor and on the board of directors of the American Council on Exercise. Before joining the Celebrity Fit Club, Smith was medical correspondent for the Today show and NBC News. Millions of viewers have watched celebrities lose as much as 41 lb. (19 kg) in a season of Celebrity Fit Club. Thus Smith's legions of fans have been accepting of his diet plan.

On April 7, 2007, Dr. Ian, as he is commonly called, launched an ongoing “50 Million Pound Challenge.” Aimed primarily at the black community, he called on 5 million people to lose 10 lb. (4.5 kg) each. As of 2012, the program had 1.5 million members and had achieved a collective weight loss of more than 5 million pounds.

See also Calorie restriction ; Protein ; Vegetarianism ; Whole grains .



Smith, Ian K. EAT: The Effortless Weight Loss Solution. New York: St. Martin's Press, 2011.

Smith, Ian K. The Fat Smash Diet: The Last Diet You'll Ever Need. New York: St. Martin's Griffin, 2006.

Smith, Ian K. The Take-Control Diet: A Life Plan for Thinking People. New York: Random House, 2001.


“The Diet Channel Interviews VH1's Celebrity Fit Club Diet Expert Dr. Ian Smith, Author of The Fat Smash Diet.” The Diet Channel. October 24, 2006. http://www.thedietchannel.com/VH1-Celebrity-Fit-Club-Diet-Expert-Dr-Ian-Smith-Fat-Smash-Diet-Interview.htm (accessed March 27, 2018).

Ian Smith official website. http://www.doctoriansmith.com (accessed March 27, 2018).

Margaret Alic, PhD

  This information is not a tool for self-diagnosis or a substitute for professional care.