Hale Handbook

Meal Replacements: Shakes, Bars and When They Make Sense

Replacing a meal or two with a measured shake works better than most people assume. Under medical care, full replacement programs have even put type 2 diabetes into remission.

2 min readUpdated November 2026Not reviewed by a doctor

The short version

  • Meal replacements remove the guesswork from a meal or two by giving you known calories and nutrients.
  • In the DiRECT trial, nearly half of people with recent type 2 diabetes reached remission after a medically supervised shake-based program.
  • Total replacement at very low calories needs medical supervision.
  • The hard part comes after, so you need a plan for returning to real food.
In a sentence
Use measured shakes or bars in place of one or more meals.
How restrictive
Counting needed?
Built in
Quality of evidence
Strong
Typical cost
Moderate
Main drawback
Returning to normal food is the hard part, and low-calorie versions need supervision

See how this compares with every other diet →

Two very different versions

Partial replacement. Replace one or two meals a day with a shake or bar, and eat a normal, sensible meal for the rest. Total intake is usually around 1,200 to 1,600 calories a day. Many people can do this on their own.

Total diet replacement. Replace all meals with formula for a set period, typically 8 to 20 weeks, often at around 800 calories a day. This is a medical program that should be run with clinical supervision.

What the evidence says

Structured replacements consistently help people lose weight, largely because they make calories simple and take decision-making out of a meal.

DiRECT was a landmark UK trial of 306 people who'd had type 2 diabetes for up to six years. The intervention group used about 850 calories a day of formula for three to five months, then gradually reintroduced food, with long-term support. At a year, 46% were in remission, versus 4% of the control group. Among those who lost at least 33 pounds, 86% reached remission.

Choosing a product, if you use one

We don't recommend brands, but here's what to look for:

  • A nutritionally complete meal replacement, not just a protein powder or snack bar
  • Around 200 to 400 calories a serving
  • At least 15 to 20 grams of protein, and some fiber
  • Low added sugar
  • Added vitamins and minerals

Shakes are ultra-processed, which is a fair criticism. The benefit in a structured program can outweigh this, but they shouldn't be your whole long-term plan.

How to use them well

  • Replace the meal you find hardest, or are most likely to skip or buy on the run.
  • Use your other meals to get vegetables, fruit and fiber.
  • Drink plenty of water.
  • Plan your transition from the beginning. Reintroduce foods gradually, and focus on building the habits you'll need afterward.

Sources

  1. Lean et al., The Lancet (2018): Primary care-led weight management for type 2 diabetes remission (DiRECT)
  2. NIDDK: Dieting and Gallstones
  3. Jensen et al., Circulation (2014): AHA/ACC/TOS obesity guideline

This guide is general information, not medical advice. Please check with a clinician before making big changes, especially if you have a health condition, take medication, or are pregnant. Read the full disclaimer.

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