Some dieters try to reduce calories by replacing meals with shakes. That's been the strategy of the SlimFast plan for over 40 years, and there are plenty of success stories. However, replacing all your meals with SlimFast isn't a sustainable or healthy plan for lasting weight loss.
Replacing all your meals with SlimFast diet shakes may result in faster weight loss, but it isn't a safe or healthy dieting strategy.
Losing Weight With SlimFast
SlimFast works by replacing two meals a day with low-calorie shakes. In addition, dieters eat one sensible meal of their choosing, and they can have three 100-calorie snacks. The aim is to make it simple to decrease calorie intake below calorie expenditure to create the calorie deficit that's required for your body to begin burning fat stores.
Each shake provides 180 calories, and each snack provides 100 calories. Two shakes and three snacks provide 660 calories. The rest of your calories should be supplied by a nutritious meal.
How many calories do you need each day to lose weight? That depends on your age, gender and activity level. According to the National Institutes of Health, most women can lose weight on a diet of 1,200 to 1,500 calories. Most men, as well as women who weigh more or exercise regularly, can lose weight with 1,500 to 1,800 calories each day.
Just Drinking SlimFast Shakes
If you drink only SlimFast shakes for breakfast, lunch and dinner, you will be consuming just 540 calories a day. That is considered a starvation diet. According to Michigan Medicine, a very low-calorie diet (VLCD) of less than 1,000 calories a day typically does not provide enough nutrients and should not be undertaken except under medical supervision.
Not eating enough calories results in nutrient deficiencies, which can have serious, even life-threatening consequences in the long term. People on VLCDs often experience fatigue, constipation, nausea and diarrhea, and they are at risk of developing gallstones. Additionally, eating too few calories can actually slow your metabolism as your body attempts to conserve energy.
Perhaps you were considering drinking seven to 10 shakes per day to meet your minimum calorie needs? That's also a potentially dangerous choice. SlimFast diet shakes are fortified with vitamins and minerals, and high intakes of some of these nutrients can have negative health effects.
For example, if you drink eight SlimFast Keto shakes each day, you'll get 48 milligrams of the mineral iron. According to the National Institutes of Health, getting more than 20 milligrams of iron each day from supplements and fortified foods may cause stomach upset, vomiting, abdominal pain, constipation, nausea and faintness.
Over time, high intakes can cause iron to build up in the blood with potentially damaging results. According to a study published in Cancer Research in November 2014, high blood levels of iron are associated with an increased risk of cancer.
Sustainable Weight Loss
Following the SlimFast diet plan as recommended can help you lose weight safely. However, ingesting only SlimFast shakes and failing to meet your calorie and nutrient needs is not a safe or sustainable way to lose weight. You may lose weight at a faster rate at first, but in the long run you are not likely to keep the weight off. People who lose weight very quickly often end up regaining all the weight they lost — and potentially more.
According to the Centers for Disease Control and Prevention, a safe and sustainable rate of weight loss is 1 to 2 pounds per week. Doing this requires creating a calorie deficit of approximately 500 to 1,000 calories per day, advises Mayo Clinic.
Many people are able to achieve that just by cutting out junk food, sweets and sugary beverages and eating more fresh fruits and vegetables, lean protein and whole grains. SlimFast shakes are highly processed dietary supplements; while they can help some people lower their calorie intake, eating whole fresh foods is always a healthier choice.
- SlimFast: "How It Works"
- National Institutes of Health: "Healthy Eating Plan"
- University of Michigan Medicine: "Weight Loss by Limiting Calories"
- SlimFast: "SlimFast Keto Vanilla Cream Shake"
- NIH: "Iron"
- Cancer Research: "High Serum Iron Is Associated with Increased Cancer Risk"
- CDC: "Losing Weight"
- Mayo Clinic: "Counting Calories: Get Back to Weight-Loss Basics"