Meal replacements and very low calorie diets: they work. That's not the hard part.
Swap your meals for shakes, soups and bars, and the weight comes off fast. Under medical supervision, it can even reverse type 2 diabetes. The hard part starts when you go back to food.
The short version
- What it is
- Replacing some meals (meal replacement) or all food (total diet replacement) with nutritionally complete shakes, soups or bars. Very low calorie diets (VLCD) go under 800 kcal a day.
- Good for
- Fast, medically supervised weight loss. Putting early type 2 diabetes into remission.
- Bad at
- Teaching you to eat. Taste. Your gallbladder, at the extreme end.
- Evidence
- Moderate to strong, when supervised. Weak for doing it alone.
- Our take
- A legitimate medical tool. Not our tool: we're about real food for life.
What meal replacements actually are
There are three levels. Partial meal replacement: one or two meals a day are a shake or bar, the rest is normal food. Total diet replacement: all food is replaced by formula products for several weeks, often around 800–900 kcal a day. Very low calorie diets: total replacement below 800 kcal a day, which is the territory where doctors are usually involved.
In the EU, products sold as total diet replacement have to meet strict rules on calories, protein, fibre, vitamins and minerals, so they can safely be someone's only food for a while.7 Your random protein shake from the gym doesn't.
After the shake phase comes "food reintroduction": a few weeks of slowly adding back real meals, followed by a maintenance programme. That last part is where it gets decided whether all this was worth it.
How it works in your body
Nothing mysterious. Very few calories, and no decisions. You can't overeat a sachet. Many people find it easier to have no food at all than a little food, because there's no "just one more bite".
After a couple of days of very low carbohydrates, many people move into mild ketosis, which can blunt hunger. The early weight loss is a mix of water (from used-up glycogen) and fat. When weight drops fast, the liver and pancreas lose fat too. That's the mechanism researchers think explains why type 2 diabetes can go into remission.
What you eat, what you don't
Eat (well, drink)
- Formula shakes, soups and bars, as prescribed
- Water, lots: two litres or more
- Black tea and coffee
- Some programmes: non-starchy vegetables
- Later: lean protein, vegetables, then the rest, step by step
Forget it
- Everything else, during the total replacement phase
- Alcohol
- Juice and soft drinks
- Supermarket shakes that aren't nutritionally complete
- Doing it for longer than the programme says
Real formula or just a shake?
The shelf is full of tubs promising "meal replacement". Most are protein shakes with good marketing. In the EU, a product meant to be your only food has to be labelled as total diet replacement for weight control and meet the compositional rules.7 If the label doesn't say that, it's not built to replace all your meals.
In Austria, Germany and Switzerland
Formula diets are sold in pharmacies and drugstores, and some doctors and clinics run supervised programmes. Start with your Hausarzt, especially if you take any medication, rather than with a drugstore shelf.
In Singapore
Start with your GP or polyclinic, not a supermarket aisle or a social media seller. Many shakes on sale here are protein or "slimming" drinks, not complete nutrition, and "slimming" products sold online deserve extra suspicion.
Alcohol on meal replacements
OK, now and then
- During total replacement: nothing
- After reintroduction: one glass of dry wine with a real meal
- A spirit with soda water and lime
Absolutely not
- Any alcohol on 800 kcal a day
- Drinking on an empty stomach
- Cocktails, beer, sweet wine
- "I saved calories, so I can drink them"
50 Club: one glass of dry wine with a full meal, weekends only.
On very few calories, alcohol hits harder, adds empty energy and can drop blood sugar, especially with diabetes medication. All the details are in our alcohol guide.
What it's good for, with proof
Weight loss, clearly
A meta-analysis of 23 trials with nearly 7,900 adults found that diets including meal replacements led to about 1.4 kg more weight loss at one year than diets without them, and about 2.2 kg more when support was added.1 Total diet replacement goes further. In a British trial, people referred by their GP to an 810 kcal total replacement programme lost 10.7 kg in a year against 3.1 kg with usual care.2 Worth noting: the formula products in both UK trials came from industry partners.
Type 2 diabetes remission
This is the headline. In the DiRECT trial, people with type 2 diabetes for less than six years did 12–20 weeks of total diet replacement (about 825–853 kcal a day), then a structured return to food and support.4 At one year, 46% were in remission, off all diabetes drugs, against 4% with best usual care.3 At two years, 36% were still in remission.4 That's real medicine, delivered by doctors and nurses.
The uncomfortable truth
"Once I hit my goal weight, I'm done." In DiRECT, remission dropped from 46% to 36% in year two, and it was tied to keeping the weight off.3,4 Among commercial very low calorie programmes, the extra weight loss also shrank after six months.6 The shakes don't teach you how to eat a Tuesday dinner. The maintenance programme has to.
"It's just a shake, I can do this on my own." The trials that worked had trained staff, medication reviews and weekly support. Doing 800 kcal on your own, especially on medication, is a different and riskier thing.
The risks
- Gallstones. In a Swedish study of over 6,000 people, a 500 kcal diet led to about three times more gallstones needing hospital care than a 1,200–1,500 kcal diet.5 Fast weight loss is the trigger.
- Medication. On diabetes or blood pressure drugs, doses often need cutting on day one, or you risk low blood sugar or low blood pressure. DiRECT stopped them under supervision.4
- Side effects. Constipation, headaches, feeling cold, tiredness, dizziness, hair thinning. Usually temporary.
- Regain. Without a solid plan for afterwards, a lot of the weight comes back.
- Eating disorders. Extreme restriction can trigger or worsen them.
Allergies: watch the staples
| Staple | Allergen (EU list of 14)8 | Swap |
|---|---|---|
| Milk-based shakes (whey, casein) | Milk | Pea or rice protein formulas; check label |
| Soy-based shakes and bars | Soy | Pea protein formulas |
| Meal bars | Peanuts, tree nuts, cereals containing gluten | Bar-free programmes, shakes or soups only |
| Instant soups | Celery, milk, cereals containing gluten | Allergen-free formula soups |
| Porridge sachets | Cereals containing gluten (oats) | Certified gluten-free oats or shakes |
Don't do meal replacements or a VLCD if you…
- are pregnant or breastfeeding
- are under 18 or over 65 without a specialist
- take insulin, sulfonylureas, SGLT2 drugs or blood pressure tablets (only with your doctor)
- have had gallstones, gout, kidney or liver disease, or a heart rhythm problem
- have ever had an eating disorder
- are not overweight
Healthen me asks about all of these and gives you a different plan if any apply.
How we use meal replacements in your plan
We don't. Meal replacements and very low calorie diets are excluded from our plans, not because they don't work, but because they work in a different way: no cooking, no food decisions, no habits. Our whole point is real food for life.
If your doctor suggests a supervised programme, especially for type 2 diabetes, take it seriously. That's medicine. Come back to us for the bit afterwards: learning to eat real meals that keep the weight off. If you're on medication for weight loss, see our page on eating on GLP-1 drugs.
This article is general information, not medical advice. If you have a medical condition or take medication, talk to your doctor before changing how you eat.
Sources
- Astbury NM et al. A systematic review and meta-analysis of the effectiveness of meal replacements for weight loss. Obesity Reviews 2019;20(4):569–587. doi.org/10.1111/obr.12816
- Astbury NM et al. Doctor Referral of Overweight People to Low Energy total diet replacement Treatment (DROPLET): pragmatic randomised controlled trial. BMJ 2018;362:k3760. doi.org/10.1136/bmj.k3760
- Lean MEJ et al. Primary care-led weight management for remission of type 2 diabetes (DiRECT): an open-label, cluster-randomised trial. Lancet 2018;391(10120):541–551. doi.org/10.1016/S0140-6736(17)33102-1
- Lean MEJ et al. Durability of a primary care-led weight-management intervention for remission of type 2 diabetes: 2-year results of the DiRECT open-label, cluster-randomised trial. Lancet Diabetes & Endocrinology 2019;7(5):344–355. doi.org/10.1016/S2213-8587(19)30068-3
- Johansson K et al. Risk of symptomatic gallstones and cholecystectomy after a very-low-calorie diet or low-calorie diet in a commercial weight loss program: 1-year matched cohort study. International Journal of Obesity 2014;38(2):279–284. doi.org/10.1038/ijo.2013.83
- Gudzune KA et al. Efficacy of commercial weight-loss programs: an updated systematic review. Annals of Internal Medicine 2015;162(7):501–512. doi.org/10.7326/M14-2238
- Commission Delegated Regulation (EU) 2017/1798 on the specific compositional and information requirements for total diet replacement for weight control. eur-lex.europa.eu/eli/reg_del/2017/1798/oj
- Regulation (EU) No 1169/2011 on food information to consumers, Annex II (the 14 allergens). eur-lex.europa.eu/eli/reg/2011/1169/oj