The diets we won't recommend: five big promises, zero good evidence.
Some diets are bad because they're hard. These ones are bad because they're wrong. Here's what each one claims, what the research found, and why none of them makes it into your plan.
The short version
- What it is
- Five popular diets we've looked at and rejected: the blood type diet, the alkaline diet, juice cleanses (including the Master Cleanse), hCG programmes, and cabbage soup and similar crash diets.
- Good for
- Selling books, juices and injections.
- Bad at
- Doing what they claim. Some are also risky.
- Evidence
- Next to none for their core claims.
- Our take
- Skip all five. Where any of them "work", it's because you ate less, and there are better ways to do that.
What these diets have in common
Each one sells a hidden mechanism: your blood group, your body's pH, "toxins", a pregnancy hormone, a magic soup. Each one comes with a story that sounds scientific. And each one, where people lose weight, does it the boring way: by cutting calories hard, often with lots of water loss in the first week.9
This page is the opposite of the rest of the site. No how-to, no 50 Club, no "half version". Just what each diet claims, what the research found, and why we skip it.
What to eat instead
Eat
- Vegetables, fruit, beans and lentils
- Fish, eggs, chicken, tofu
- Wholegrains, potatoes, olive oil, nuts
- Whole fruit instead of juice
- Water, tea, black coffee
Forget it
- Diets based on your blood group
- Alkaline water and pH test strips
- Juice-only "cleanses" and detox teas
- hCG drops, sprays and injections for weight loss
- Any diet built on one food for a week
1. The blood type diet
The claim: each blood group (O, A, B, AB) evolved at a different time, so each should eat differently. Type O should eat like a hunter with lots of meat, type A like a farmer, mostly vegetarian, and so on.
The evidence: a systematic review screened over 1,400 studies and found no study at all showing health effects of eating for your ABO blood type.1 A later study of 1,455 people found that some of the "blood type" diets were linked to better health markers, but it didn't matter what blood type people actually had.2 The type A diet is basically a healthier diet, so it helps anyone who eats it.
Why we skip it: it's built on a theory that doesn't hold, and it can cut out healthy foods for no reason.
2. The alkaline diet
The claim: modern food makes your body "acidic", causing everything from weight gain to cancer and osteoporosis. Eat "alkaline" foods (vegetables, fruit) and drink alkaline water to fix it.
The evidence: your blood pH is tightly controlled by your lungs and kidneys, and food doesn't meaningfully change it in healthy people. A systematic review of diet acid load, alkaline water and cancer found almost no research at all, and no trials.3 On bone, a meta-analysis testing the "acid-ash" idea found that the supposedly acidic mineral phosphate didn't increase calcium loss from the body; it decreased it.4
Why we skip it: the theory is wrong. The good part (eat more vegetables and fruit) doesn't need the theory.
3. Juice cleanses and the Master Cleanse
The claim: a few days on only juice, or on the Master Cleanse (a lemon, maple syrup and cayenne pepper drink, plus salt water and laxative tea), flushes out toxins and resets your body.
The evidence: a critical review of detox diets found very little clinical evidence, flawed small studies, and no randomised trials of commercial detox diets in humans.5 Your liver and kidneys already handle "detox", every day, for free.
Why we skip it: almost no protein, almost no fibre, a lot of sugar, and any weight lost is mostly water.9 And it isn't always harmless: doctors have described acute kidney failure from heavy juicing of oxalate-rich vegetables like spinach and beetroot, especially in people with existing kidney disease.6
4. hCG diets
The claim: injections, drops or sprays of hCG (a pregnancy hormone) plus a 500-calorie-a-day diet let you lose fat fast without hunger, and from "the right places".
The evidence: a meta-analysis of the controlled trials concluded there's no scientific evidence that hCG causes weight loss, redistributes fat, reduces hunger or improves wellbeing.7 The weight loss comes from the 500 calories. The US Food and Drug Administration says over-the-counter "homeopathic" hCG products are illegal, no hCG product is approved for weight loss, and the very low calorie diet that comes with them carries risks like gallstones, electrolyte imbalance and irregular heartbeat.8
Why we skip it: a hormone that does nothing for fat loss, attached to a starvation diet that does real harm. Hard pass.
5. Cabbage soup and other crash diets
The claim: eat as much cabbage soup as you like, plus a short list of other foods, for seven days, and lose up to 5 kg.
The evidence: we couldn't find a single controlled trial of the cabbage soup diet. What happens is simple. You eat very few calories, you use up your stored carbohydrate (glycogen), and the water stored with it goes too. That's most of the "kilos" in week one, and it comes back when you eat normally again.9
Why we skip it: it teaches nothing, it's low in protein, and repeated crash dieting is miserable. Very low calorie diets also raise the risk of gallstones.10
Alcohol
None of these diets has a sensible alcohol policy, because none of them is a way of life. If you drink, see our alcohol guide.
How to spot the next one
These five won't be the last. A new miracle diet turns up every January, usually with a celebrity and a discount code. Before you buy in, check for these red flags:
- A hidden cause nobody else has found. Toxins, pH, blood group, "hormone resets". If one secret explains all weight gain, it's marketing.
- A product you have to buy. Drops, teas, shakes, test strips, a "programme". The diet exists to sell the product.
- Fast results, short time frame. "Lose 5 kg in 7 days" means water and glycogen, not fat.9
- Whole food groups banned for no medical reason. Fruit, grains or legumes don't become dangerous because a book says so.
- Testimonials instead of trials. Before-and-after photos are not evidence. Ask for the randomised trial. There usually isn't one.
What to do instead
If the goal is weight, the boring version wins: a modest calorie cut you can live with, a proper portion of protein at each meal, plenty of vegetables, and fewer sweet drinks and snacks. Patterns like the Mediterranean diet give you that without a gimmick. If the goal is "feeling better" or "detox", start with sleep, water, less alcohol, more movement, and a check-up if something feels off. None of it fits on a juice bottle label, which is exactly the point.
The uncomfortable truth
"But my friend lost 5 kilos on it." Very likely true. Almost any diet that cuts calories hard makes the scale drop in week one, mostly water.9 The question isn't "did the scale move?" It's "is the reason they give the real reason, and will it last?" For these five, the answers are no and no.
The risks
- Very low calorie diets (hCG, cabbage soup, juice-only): gallstones, dizziness, muscle loss.8,10
- Kidney damage from heavy juicing of oxalate-rich vegetables in vulnerable people.6
- Laxatives in some cleanses: dehydration and salt imbalance.
- Unregulated hormone products bought online.8
- Missed real problems. Tiredness, bloating or weight gain blamed on "toxins" or "acidity" can be signs of something your doctor should check.
Allergies: watch the staples
| Staple | Allergen (EU list of 14)11 | Note |
|---|---|---|
| Celery juice and celery in cabbage soup | Celery | Celery is a major allergen; another reason to skip |
| Nut milks in cleanse packages | Tree nuts | Check every bottle |
| Stock cubes in cabbage soup | Celery, often cereals containing gluten, milk | Check labels |
| Dried fruit and wine in "alkaline" plans | Sulphur dioxide and sulphites | Check labels |
Don't do any of these if you…
- are pregnant or breastfeeding
- have diabetes, kidney disease or a heart condition
- take regular medication
- have ever had an eating disorder
- are under 18
Honestly: don't do them at all. Healthen me gives you a real plan instead.
How we use these diets in your plan
We don't, and we won't. These diets are excluded. Not because they're too strict, but because their core claims don't stand up and some of them carry real risks.
If you want something that sounds a bit like them but works, look at Sirtfood (good food list, shaky theory), supervised meal replacements (real medicine for some people), or just a plate full of vegetables, protein and olive oil.
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
- Cusack L et al. Blood type diets lack supporting evidence: a systematic review. American Journal of Clinical Nutrition 2013;98(1):99–104. doi.org/10.3945/ajcn.113.058693
- Wang J et al. ABO genotype, ‘blood-type diet’ and cardiometabolic risk factors. PLoS One 2014;9(1):e84749. doi.org/10.1371/journal.pone.0084749
- Fenton TR, Huang T. Systematic review of the association between dietary acid load, alkaline water and cancer. BMJ Open 2016;6(6):e010438. doi.org/10.1136/bmjopen-2015-010438
- Fenton TR et al. Phosphate decreases urine calcium and increases calcium balance: a meta-analysis of the osteoporosis acid-ash diet hypothesis. Nutrition Journal 2009;8:41. doi.org/10.1186/1475-2891-8-41
- Klein AV, Kiat H. Detox diets for toxin elimination and weight management: a critical review of the evidence. Journal of Human Nutrition and Dietetics 2015;28(6):675–686. doi.org/10.1111/jhn.12286
- Getting JE, Gregoire JR, Phul A, Kasten MJ. Oxalate nephropathy due to ‘juicing’: case report and review. American Journal of Medicine 2013;126(9):768–772. doi.org/10.1016/j.amjmed.2013.03.019
- Lijesen GK et al. The effect of human chorionic gonadotropin (HCG) in the treatment of obesity by means of the Simeons therapy: a criteria-based meta-analysis. British Journal of Clinical Pharmacology 1995;40(3):237–243. doi.org/10.1111/j.1365-2125.1995.tb05779.x
- US Food and Drug Administration. HCG diet products are illegal. Consumer Update, December 2011. www.fda.gov/consumers/consumer-updates/hcg-diet-products-are-illegal
- Kreitzman SN, Coxon AY, Szaz KF. Glycogen storage: illusions of easy weight loss, excessive weight regain, and distortions in estimates of body composition. American Journal of Clinical Nutrition 1992;56(1 Suppl):292S–293S. doi.org/10.1093/ajcn/56.1.292S
- 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
- Regulation (EU) No 1169/2011 on food information to consumers, Annex II (the 14 allergens). eur-lex.europa.eu/eli/reg/2011/1169/oj