Diet Failure Statistics 2024 | Why Do Diets Fail?

a thin woman next to a fatter woman, and text 'Diet Failure Statistics'

If it seems like every other person you know, including yourself, has tried to diet, you’re not wrong. 42% of all people are actively trying to lose weight. Not “have tried in the past” or “are thinking about it in the future.” Rather, nearly half of all adults are trying to shed pounds, right this minute.

It’s staggering to find out, then, that the overwhelming majority of diets end in failure. Depending on the numbers and source, either one-third of dieters return to their old weight, or as many as 65% do.

Our other articles will focus on which diets are trending, and overall weight loss statistics in the US; this article will bear down on only the failure statistics.

How Many Diets Fail, and By How Much

One of the most common measuring sticks for a diet failing is weight regain after a certain period of time. The Journal of Clinical Nutrition [1] has compiled data from a registry of volunteers, and here are some of their findings.

  • After one year, 35% of people regain at least 5 lbs.
  • 59% maintained their weight.
  • Only 6% continued to lose weight.
  • Maintaining weight loss for 2 consecutive years decreases weight gain odds by 50%.
  • People with no medical event triggering weight loss regain weight 50% more than those with a medical event.

Meanwhile, more nuanced data was taken from a different population by the Medical Clinics of North America. [2] These data are compiled from an analysis of dozens of diet groups, spanning thousands of participants. 

  • More than half of all weight lost in diets is regained within 2 years.
  • By year 5, more than 80% of all weight lost is regained.

Another set of studies quoted by UCLA found that:

  • In less than two years, 23% of people gain more weight than they lost.
  • More than two years after dieting, 83% gain more than they lost.
  • A final study followed up on dieters after 5 years, and 50% of them were 11 pounds over initial weight.

Why Diets Fail

Some diets fail because they are inherently ineffective, some fail because of individual factors.

  • The average diet for women lasts only 4 weeks
  • The  average diet for men lasts only 6 weeks.
  • Diets where people are told not to eat a certain food increase overeating that food by 133%. [3]

Some diets fail because of the misunderstanding of changes in the body:

  • For every kilogram (2.2 lbs) of weight lost:
    Calories spent by the body decreases by 20 kcal/day, but appetite increases by 100 kcal/day.
  • Calorie intake can fluctuate by 20-30% on a diet, sending mixed signals to the brain about appetite.
  • Eating only an extra 100 calories a day more after dieting can result in substantial weight gain.
  • Without maintenance visits with doctors, dieters regain over 5% of their weight back between 5 and 15 months. [4]
  • 95% of people who completely cut one thing out (no carb, or only liquid) regain their old weight.

This can explain why people do not keep their weight off; their appetite is increasing while their calorie needs are actually decreasing.

Repeated Diet Failures

One of the datum to track to conceptualize diet failure is the number of people who have tried to diet multiple times. Logically speaking, if a first or second diet succeeds it obviates the need for a subsequent diet attempt.

  • 24% of people have tried to lose weight one or two times in their life.
  • 28% have tried to lose weight 3 to 10 times.
  • 11% have tried more than 10 times.

How People Diet

Ascertaining whether someone is dieting alone, or in conjunction with multiple disciplines, can give insight as to their success, as well as what types of dieting the engage in. [5]

  • 10% of people attempt to diet without any exercise or program.
  • The most common diet is:
    1. Restricting certain foods (87.6%)
    2. Limiting quantity (44%)
    3. Counting calories (43%) - Of these people, 25% count fat, 20% use a formula, and 22% use an 'exchange program' such as Weight Watchers.


Much of the research into diet failure is subsumed into larger data frameworks of weight loss, obesity, and fitness as a whole. Those data will be compiled in future articles.


People Also Read...

Recent Articles

About the Author

Sam is a passionate health and fitness enthusiast who has been interested in supplements, fitness, and wellness for over 10 years. He is the founder of Great Green Wall - the health and wellness brand and has completed multiple fitness certificates, including personal training and nutrition certifications. Sam has been working as a personal trainer for the past three years and is dedicated to helping his clients achieve their fitness goals and lead healthier lifestyles. He believes that a healthy lifestyle is crucial to a happy and fulfilling life and is committed to sharing his knowledge and passion with others.

{"email":"Email address invalid","url":"Website address invalid","required":"Required field missing"}