If you’ve been directed to this post, it’s probably because we’re discussing if there’s any practical, sustainable, healthy way for a typical fat person to choose to no longer be fat. As part of this discussion, I’ve asked you to refer me to peer-reviewed studies demonstrating that a typical fat person can become sustainably non-fat through deliberate effort (whether you call that a “diet” or a “lifestyle change”). Since so many people believe this to be indisputable fact, I don’t think it’s out of line of me to ask for good-quality evidence.
Let me explain what I’m not looking for. These are things that are not evidence that becoming and remaining non-fat is reasonably possible for a typical fat person.
NO ANECDOTES PLEASE
I’m not looking for anecdotes. I’m looking for peer-reviewed studies.
Obviously, thousands of fat people have become non-fat, perhaps including yourself. And that’s fine. I sincerely wish that all of those ex-fat-people find sustained happiness and health.
However, since millions of people diet and fail to become non-fat, that there are many such anecdotes of weight-loss doesn’t actually tell us anything about what would happen for a typical fat person. Your own personal experience (or that of people you know, or people you know of) may not be generally applicable.
SIGNIFICANT AMOUNTS OF WEIGHT LOST
To count as evidence, a study would need to demonstrate that a majority of fat subjects were able to become so-called “normal” weight1 – that is, they’re no longer fat – through intentional weight-loss.
Most studies about weight loss have extremely forgiving standards of “success.” A study demonstrating that most fat subjects were able to lose 6 pounds or thereabouts isn’t what I’m looking for. Fat people are still fat even if we lost two to ten pounds. A study demonstrating that fat people can lose a few pounds doesn’t establish anything at all about if a typical fat person can become non-fat.2
See, for example, this study, which declares “research has shown that 20% of overweight individuals are successful at long-term weight loss when defined as losing at least 10% of initial body weight and maintaining the loss for at least 1 y. ” Well, I weigh 330 pounds. If I lost 10% of my weight, that would make me 297 pounds – which is to say, I’d still be fat. (Also, a 20% success rate is not very impressive.)
WEIGHT LOSS WHICH LASTED AT LEAST FIVE YEARS
Another problem with that study I just quoted? “For at least 1 year” isn’t a very impressive claim, if we’re looking for evidence of sustained weight loss. I’m asking you for studies showing weight loss that’s maintained for at least five years, and a ten-year follow-up would be better.
This is important, because almost any weight-loss plan works for a few months or a year – which is the length of follow-up many, if not most, weight loss trials use. For the purpose of asking if sustainable weight loss is possible, it’s not meaningful unless the study can show the loss is sustained over the long term.
MOST PARTICIPANTS DIDN’T DROP OUT
I’ve seen a lot of studies claiming to show a successful weight-loss program – but when I look at the details, 75% of the study’s subjects dropped out before the study was complete. This is a problem because the people who drop out of a weight loss program are not a random selection – they are more likely to be the people who found the program wasn’t doing anything for them.
NOT A STUDY OF ONLY SUCCESSFUL DIETERS
Suppose I did a study of professional basketball players. My study shows that a typical NBA player exercises a lot and practices at basketball a lot. Therefore, I say, a typical person can become an NBA player by exercising a lot and practicing basketball a lot. That would be self-evidently ridiculous. The people who can successfully become NBA players are outliers; we can’t assume that a typical person who follows Lebron James’3 exercise and practice routine would experience James’ success.
Yet very often, when I ask for evidence that a typical fat person can stop being fat, people cite studies using data from The National Weight Control Registry. The NWCR “is a research study that includes people (18 years or older) who have lost at least 13.6 kg (30 lbs) of weight and kept it off for at least one year… On average, registry members have lost about 70 pounds and kept it off for five and a half years when joining the registry.”
In other words, to be part of the NWCR’s data, you have to already be an outlier. Just as NBA players are outliers, the NWCR participants are outliers. A study of self-selected outliers can’t tell us anything about whether a typical fat person is able to stop being fat.
PLEASE DON’T TELL ME ABOUT THERMODYNAMICS
That’s not a study, and not what I asked for.
Look at it this way – suppose I had asked you for an example of a spaceship that can successfully take living human beings to Venus and back. You might have many reasons, rooted in an understanding of physics, to believe that such a spaceship is definitely possible. But that’s not the same as demonstrating that such a ship has actually been built and successfully operated.
I’m not asking you for what’s possible in principle. I’m asking for documentation that there is a weight-loss approach that has been tried in the real world, and has been shown to successfully cause most fat people to stop being fat people, in a sustainable fashion.
Thanks for reading! Now that you’ve read all this – and thanks, sincerely, for your patience – I look forward to seeing your evidence.
- Weight Science: Evaluating the Evidence for a Paradigm Shift | Nutrition Journal | Full Text
- Medicare’s Search for Effective Obesity Treatments: Diets Are Not the Answer [eScholarship]
- Miller, W. C. How effective are traditional dietary and exercise interventions for weight loss? Med. Sci. Sports Exerc. 31, 1129-1134
- The science is in: exercise won’t help you lose much weight – Vox
- Diets do not work: The thin evidence that losing weight makes you healthier.
- Odds of a severely obese woman becoming “normal” weight: 1 in 677. For men, 1 in 1290. | Alas, a Blog
- Why the “war on fat” is a scam to peddle drugs – Salon.com
- The Case Against Weight-Loss Dieting | Alas, a Blog
- Do 95% of Dieters Really Fail? | Dances With Fat
- Seriously, Weight Loss Doesn’t Work | Dances With Fat
- Why Don’t You Like My Studies? | Dances With Fat
- Why Do Dieters Gain Their Weight Back? | Dances With Fat
- National Weight Control Registry – Skydiving Without a Chute | Dances With Fat
- The Fat Trap – The New York Times
- All diets work the same: poorly | Shapely Prose
- Calories In/Calories Out? Science Says No | Dances With Fat
- Why You Can’t Lose Weight on a Diet – The New York Times
- Diets Don't Work, So Why Do We Still Pretend They Do?
Top image: painting by Fernando Botero.
- “Normal” weight, in most studies, refers to people with BMIs of between 18.5 and 24.9. I have issues with BMI, but for the narrow purposes of this post, I’ll accept that standard. [↩]
- If you want to argue that losing those few pounds is nonetheless worthwhile, that’s fine; but that still doesn’t demonstrate that it’s possible for most fat people to stop being fat. [↩]
- I know the name of a basketball player! [↩]