There Is No 'Best' Way To Lose Weight
The best diet is probably the one that works for you
The world of dieting is a fascinating one. If you’re following the latest celebrity trends, what you should be eating changes almost weekly. This is always referenced back to some scientific finding, even though the evidence on dieting hasn’t shifted all that much for at least a decade, maybe more.
As an epidemiologist, dieting is interesting because it’s a complex topic that impacts a huge number of people in one way or another. As a human being who has in his life gone on many a diet, and ultimately managed to lose about 20kg long-term, I find the endless to-and-fro of popular diet fads both slightly depressing and extremely compelling to watch.
People are always looking for a silver bullet, and the diet space is no different. Should you try low-carb or low-fat? Mediterranean or Paleo? Is it better to cut out meat entirely, or eat nothing but beef as some steroid-taking Tiktok influencers have suggested?
These messages are wildly different but also remarkably identical. They all claim that there is one single thing which you can do to improve your life. Forget the complexity, forget the challenges - just do This One Simple Trick and you’ll lose weight and look like the guy on Instagram with bulging muscles and a weird obsession with his own name.
Unfortunately, the evidence doesn’t really support simple tricks. When it comes to health, there generally aren’t any silver bullets around.
Losing Weight Scientifically
I’ve written about weight loss regimens before, but this time it was influenced by a new study that came out recently. This paper was a small randomized trial that compared calorie-counting with intermittent fasting, and after 12 months of dieting found that both diets worked better for weight loss and metabolic health than no diet, but were essentially the same as each other.
Now, this particular paper isn’t evidence of much. It’s a very small study, and at best just adds a little bit more information to the general body of evidence on specific diets. It’s the sort of humdrum finding you see every day, that is only making news because people still claim that intermittent fasting is The One True Diet and so any story about it gets a bunch of clicks. In a sane world, finding that intermittent fasting was basically the same as calorie-counting would be the sort of boring finding that couldn’t make news if it tried.
Sadly, the world we live in is anything but sane.
We’ve known for ages that most diets are equivalent to each other when you test them rigorously. It’s not a secret. It’s been at least a decade since the evidence became pretty conclusive that, in practice, any one diet is probably the same as another. But you can’t get curious eyes on your book and money in your pocket by saying “try my diet, it’s probably about the same as all the rest of them”, so we keep hearing about why the latest fad is finally the one that will work.
This isn’t my opinion - the evidence is really quite strong. Take this Cochrane review looking at low-carb vs high-carb diets for weight loss and cardiovascular health. They found minimal differences between the two strategies for either losing weight or other health impacts. Cochrane is usually considered the gold standard for evidence-based medicine, and it’s hard to see a serious argument against their results. Some would probably say that the included diets weren’t ‘low-carb’ enough, but to me that’s extremely unconvincing - if reducing carbohydrates in your diet has a large benefit, then you’d expect to see some improvement regardless of how much they’re restricted.
This isn’t a standalone finding. Other diets suffer from the same lack of discernable differences. A systematic review and network meta-analysis from 2018 showed precisely this finding. Network meta-analyses are a special type of study where you combine all of the studies that compared different treatments to one another in such a way as to be able to compare things that weren’t necessarily studied in the same paper. If A is better than B in paper 1, and B is better than C in paper 2, then you can infer that A is likely better than C even if they’re never directly compared. Obviously this is a complex statistical process, but what you end up with is a reasonable idea of which treatment is the best of a bunch.
This review found that the five diets studied were pretty much identical in terms of outcomes. The Mediterranean diet had some slight benefits over a fat-reduced diet, but otherwise everything was pretty similar across the board. And while I have some methodological quibbles with the review itself - I usually do - this is hardly the only paper to show similar results.
A similar systematic review and network analysis found that meal frequency and timing seems to have very little impact on either energy intake or weight. A large, cross-country randomized trial showed that neither increasing protein nor decreasing glycemic index had much of an additional benefit for either weight or the prevention of diabetes. Yet another systematic review found that neither low-carb nor very low-carb diets had a benefit on diabetes control at 12-24 months, despite some minor improvements over other diets at 6 months.
Given enough time, most diets blend together in clinical trials. You could argue this is because the people in those trials aren’t achieving some perfect ideal of low-carbohydrate cuisine, but frankly no one cares about perfection. We care about real people in the real world trying to lose weight in the boring everyday circumstances we all face. If the only diet that works requires people to embrace perfection, then it will never be effective for the vast majority of people who try it out.
Bottom Line
Firstly, it’s important to remember that weight loss isn’t everything. But where weight loss is the goal, what we know suggests that pretty much anything you do will be equally effective. You might lose an extra kilo or two by trialing some new fad, but overall it’s probably going to even out to basically the same result.
This is why my advice for anyone looking to shed a few pounds is always that you should do what works for you. Personally, I’ve lost weight through several different diets, and kept it off mostly through calorie counting and some intermittent fasting, but those aren’t for everyone.
If you want to lose weight, the evidence shows that it probably doesn’t matter if you go low-carb, low-GI, or low-calorie - everything is pretty much the same.
What matters is how it fits in your life.