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Fad Diets Facts & Statistics - Everything You Need to Know

Isaac Robertson
Published by Isaac Robertson | Co-Founder & Chief Editor
Fact checked by Donald Christman, BHSc FACT CHECKED
Last updated: February 27, 2023

The unfortunate reality is that the weight loss sector is full of bad ideas and products, and too many vulnerable people fall for lofty promises.

In many cases, they jump on so-called “fad diets” without a clear understanding of what they are letting themselves in for.

But the term “fad diet” is often thrown out with very little research into whether there is evidence to support them.

So our research team at Total Shape decided to look into the diets that are most commonly called fad diet to see whether there are facts to support such claims.

We started our research by defining a fad diet as a diet that is popular for a relatively short time, and it is often “sold” as the fastest way for losing weight.

Quick Summary

  • The intermittent fasting goal is not eating for 12 hours in order to support weight loss, and fad studies reveal over 38% drop from this fad diet.
  • Paleo diet limits your food choices to improve your health and support weight loss.
  • Keto diet fad facts state that people cannot limit their carbs intake for a long period.
  • The carnivore diet fad facts reveals that people find it difficult to only survive on only animal products.

10 Fad Diets Under Scientific Scrutiny

We’ve taken 10 of the most highly covered diets of the last couple of years and looked for scientific evidence in support of them.

1. Intermittent Fasting

white clock and a hand pointing at it
  • Goal is not eating for 12+ hours a day by not consuming calories after 7 pm and pushing breakfast out to 9 am.
  • Scientific studies support this kind of weight loss plan as effective with the average weight reduction from trial being 7-11 lbs over 10 weeks [1].
  • The reason this has probably fallen into the fad category is that the dropout rate during studies was very high at 38% [2].

2. Paleo Diet

  • Based on the concept that you should limit your food choices to what our hunter-gatherer ancestors would have had available.
  • Promoted as a way to lose weight and improve heart health, diabetes, and digestion problems.
  • Studies have shown that it works for weight loss and balancing blood sugar levels with a 22% reduction of insulin over 6 weeks [3].
  • Researchers also showed that it worked well for reducing blood pressure (down 15-19 mmHg) and cholesterol (down 39%) [4].
  • Dropout rates tend to be high due to the cost factor of organic and grass-fed foods.

3. Keto Diet

bowl full of tomato and cabbage
  • Involves limiting your carbohydrate intake to less than 50 grams per day to force your body into ketosis.
  • Ketosis burns fat instead of carbs for fuel and can help with weight loss, which is supported by studies that have shown a 10-13% fat reduction in trials [5].
  • Often classed as a fad because most people simply cannot sustain the severe elimination of carbs for the long-term.

4. Carnivore Diet

  • Involves eating nothing but animal products, which means steak for breakfast, ground beef with bacon for lunch, and some liver or other organ meat for dinner with no sides.
  • There’s overwhelming evidence that this kind of diet will cause serious issues for your heart health because 20% of calories from fatty meat come from saturated fat [6].
  • The long-term effects of not eating everything your body needs are also rather concerning.

5. Atkins Diet

uncooked pasta in a bowl with an anti sign
  • Popular 1990s diet aims to eliminate carbs from your diet and stop your body from producing fat storage.
  • Studies have shown that it can help you lose weight quite fast, but they also highlighted significant issues with bad cholesterol increasing by 44% in some trials [7].
  • The extreme reduction of carbs is also why so many people bail out of this weight loss plan, similar to keto.

6. Alkaline Diet

  • Claims that you can boost your weight loss by eliminating acidic foods and aiming to eat at least 80% alkaline foods.
  • Studies have highlighted that the longer-term effect of this diet could be a severely limited intake of vital vitamins and minerals [8]. 
  • Limited evidence that it’s the reduced acid intake that helps you lose weight, rather than eliminating many processed and sugary foods.

7. Mediterranean Diet

plate of melon slices
  • Primarily a diet for preventing heart disease by focusing on healthy vegetables and fruit while limiting unhealthy fats and meat.
  • One extensive study proved that it reduced risks of heart disease and strokes by up to 30% [9].
  • Sometimes classed as a fad diet because of limited weight loss impacts.

8. Zone Diet

  • Provides strict goals of eating 40% carbs, 30% protein, and 30% fat in every meal.
  • Doesn’t restrict any specific types of foods, including sugar, which may explain limited results.
  • Studies have revealed a lot of doubts over the efficacy with some around physical performance levels dropping by 10% when measured in VO2Max [10].

9. Raw Food Diet

plate full of fresh fruit and nuts
  • Mainly plant-based diet that focuses on eating raw fruits, veg, nuts, and seeds with no cooking involved.
  • Studies have shown that this approach can significantly reduce total cholesterol (-10%), but this includes the good cholesterol the body needs, which went down by 10% in a test group [11].
  • Knowledge of long-term effects is limited as few people stick with this diet approach.

10. Nutrisystem

  • Based on the concept of eating six small meals to avoid snacking on sugary treats and junk food. 
  • Studies have shown that followers of the diet lost 4% more weight than the control group [12].
  • Joining an organized Nutrisystem program is quite expensive, which is probably why many people don’t last longer than trial periods.

Related Articles:

Focus On Avoiding True Fad Diets

There are two things to keep in mind.

Firstly, if you have been struggling with weight loss, then you’re more likely to fall for fad diets. Secondly, if it sounds too good to be true, then it probably is.

There simply is no easy way out of reducing body fat; it requires plenty of physical activity combined with a balanced diet of healthy foods.


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