Slim-Fast Diet Expert Reviews

Star ratings reflect scores of 1 to 5 assigned to Slim-Fast in seven categories by nutritionists, specialists in diabetes and heart disease, and other diet experts on a ratings panel assembled by U.S. News. (See our Best Diets methodology.) The diet was judged as relatively well-designed to produce both short- and long-term weight loss, and according to experts, it’s relatively nutritionally sound and safe. It offers structure and convenience, but Slim-Fast products could grow old after a while, making long-term adherence difficult. Below, ratings in all categories and how the experts’ opinions broke down.

Overall Score 3.3

Short-Term Weight Loss

21 Ratings
5 Star
(2)
4 Star
(8)
3 Star
(9)
2 Star
(1)
1 Star
(1)

Score 3.4

Slim-Fast will likely deliver fast results thanks in large part to its 1,200-calorie-a-day regimen. It earned nearly 3½ points out of 5, topping many other ranked diets. Experts said it’s an effective way to lose weight in the short term.

Long-Term Weight Loss

21 Ratings
5 Star
(1)
4 Star
(7)
3 Star
(9)
2 Star
(4)
1 Star
(0)

Score 3.2

Slim-Fast is a sustainable diet, according to experts, and there’s a decent chance dieters will maintain significant weight loss for two years or more. The popular meal-replacement program pulled in more than 3 out of 5 possible stars, outperforming a large majority of other diets.

Easy to Follow

21 Ratings
5 Star
(2)
4 Star
(4)
3 Star
(12)
2 Star
(3)
1 Star
(0)

Score 3.2

Slim-Fast takes the guesswork out of dieting. Grab a meal bar or shake and you’re good to go. While the products could grow repetitive, you can spice things up with restaurant meals and the occasional splurge. “This plan makes living a normal life outside of a can or bar difficult,” according to one expert. Still, it outshined many competitors in this category.

Nutrition

21 Ratings
5 Star
(0)
4 Star
(11)
3 Star
(8)
2 Star
(1)
1 Star
(1)

Score 3.4

Slim-Fast conforms relatively well to government nutritional recommendations, and experts gave it middle-of-the-road reviews on how nutritionally sound it is. The company’s products are packed with various nutrients, but dieters only get a low 1,200 calories a day.

Safety

21 Ratings
5 Star
(0)
4 Star
(14)
3 Star
(7)
2 Star
(0)
1 Star
(0)

Score 3.6

Slim-Fast pulled in its highest score in the safety category. Health risks, like malnourishment and excessively rapid weight loss, aren’t major concerns. Nevertheless, dieters under the age of 18 should steer clear, experts said, because 1,200 calories a day isn’t appropriate for children and young adults who are still growing.

For Diabetes

20 Ratings
5 Star
(0)
4 Star
(5)
3 Star
(14)
2 Star
(1)
1 Star
(0)

Score 3.2

Slim-Fast earned more than 3 out of 5 stars from experts, consistent with research suggesting it can help prevent or manage diabetes. The program has been described as a safe and effective way to improve glucose and insulin levels, which are important measures for diabetics.

For Heart Health

20 Ratings
5 Star
(0)
4 Star
(2)
3 Star
(11)
2 Star
(7)
1 Star
(0)

Score 2.8

Slim-Fast received its worst score in the heart category. At best, the program is likely to have a modest effect on cardiovascular health, according to experts. Still, some research suggests meal-replacement diets can help lower total and LDL cholesterol, as well as blood pressure. When these levels are high, the risk of heart problems increases.



Last updated by Angela Haupt | December 12, 2013

Best Diets Rankings

Best Diets Overall
Diets ranked by across-the-board effectiveness.

Best Weight-Loss Diets
Diets ranked by effectiveness for both quick and lasting weight loss.

Best Diabetes Diets
Diets that can prevent diabetes or help diabetics.

Best Heart-Healthy Diets
Diets that lower cholesterol, blood pressure or triglycerides.

Best Diets for Healthy Eating
Diets ranked by how safe and nutritionally complete they are.

Best Commercial Diet Plans
Brand-name diets ranked by overall effectiveness.

Easiest Diets to Follow
Diets ranked on whether they're a snap to stick to.

Best Plant-Based Diets
Plant-based diets ranked by overall effectiveness.

Connect with U.S. News Health

See more Eat + Run posts »