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SlimFast may be one of the most long-standing diets that is based on meal replacement products. The 3-2-1 Plan includes 3 snacks, 2 meal replacements (bars or shakes), and 1 500-calorie meal per day. Snacks can be Jenny Craig snack bars, nuts, or fruit. Meal replacements are high-protein. The 500-calorie meal consists of vegetables, lean protein, and a starch.



This is a convenient diet that doesn’t make you do tricky meal planning.

  • At about 1,200 calories per day, it’s a low-calorie diet that’ll let you lose weight.
  • This is a simple diet that doesn’t require much cooking. You just need to eat bars, meal replacement shakes, and a single meal each day.
  • If you like sweets, this is a good way to go. Meal and snack bars and meal replacement shakes come in flavors like chocolate caramel, yogurt honey, chocolate almond, and chocolate peanut butter.
  • Jenny Craig products are highly fortified with vitamins and minerals, so they can help prevent nutrient deficiencies after weight loss surgery.


  • You need to buy bars and shakes. If you can’t find them at a local grocery store, you’ll need to buy them online.
  • It’ll be tough to get enough protein.
  • Your nutrients mainly come from processed bars and shakes, not from naturally healthy foods. You could miss out on other healthy nutrients like omega-3’s from fish, probiotics from yogurt, and antioxidants from whole grains, beans, and fruits and vegetables.
  • You might be hungry. You get only one meal a day, plus bars, small snacks, and shakes. A snack bar is about an ounce – not very filling.
  • Some bars and meal replacement shakes are high in sugar and artificial sweeteners.

SlimFast 3-2-1 PLan and Weight Loss Surgery

You can’t necessarily follow SlimFast 3-2-1 and stick to a weight loss surgery diet. That’s because the single meal may be too large for weight loss surgery patients. It has 500 calories, which is one-half or one-third the total number of calories many weight loss surgery patients eat in a day. The meal can weigh half a pound (8 ounces) or more, when the size of your stomach, sleeve, or pouch after weight loss surgery may be only 2 to 4 ounces.

It has you eating six times a day. Some of the allowed snacks, such as peanuts and nuts, contain protein. Others, like fruit, don’t. The diet’s snack bars are low-protein, making this diet more likely to leave you hungry and become protein-deficient.

If you want to use SlimFast after weight loss surgery

  • Modify it and choose high-protein, low-calorie snacks instead of snack bars or plain fruit.
  • Consider breaking the 500-calorie meal into two smaller meals.
  • Choose lower sugar varieties of bars and shakes – read the labels.