Scroll through social media for five minutes and somebody will tell you that skipping breakfast is the secret to burning fat, sharpening your brain and living longer. Often right before they try to sell you an app, a powder or a coaching program.
Plenty of people are listening. In a 2025 survey of 3,000 adults by the International Food Information Council, 57% said they’d followed a specific diet in the past year, up from 36% in 2018. Intermittent fasting tied calorie counting at 15% — roughly 1 in 7 American adults.
I’ve watched diet fads come and go for more than 35 years. I’ve even fallen for one myself — I tried the Atkins diet years ago. So when something gets this popular this fast, my first question is always the same: Where’s the proof?
Turns out, researchers have been asking the same thing. Here’s what they found.
Fasting works about as well as cutting calories — no better
Last year, researchers published what Harvard’s School of Public Health called the largest systematic review of intermittent fasting, in The BMJ, a leading medical journal. They pooled 99 randomized clinical trials covering 6,582 adults.
Their conclusion, according to Harvard, whose researchers co-wrote the study: For weight loss, fasting and old-fashioned calorie cutting were on par. Both beat eating whatever you want.
Then in February, a second team took a crack at it. The Cochrane Collaboration, a nonprofit that reviews medical research, looked at 22 trials involving 1,995 overweight or obese adults.
Its verdict was even blunter. The Cochrane reviewers found fasting didn’t make a clinically meaningful difference in weight loss compared with standard diet advice. Or compared with doing nothing at all.
Why? Here’s my take: Fasting isn’t magic. It’s a way to eat less. Close the kitchen for 16 hours, and you’ll probably eat fewer calories. That’s the whole trick — and it’s the same trick every diet in history has used.
The every-other-day crowd gets a tiny edge
There was one bright spot in the big BMJ review. People who fasted every other day — a fast day of little or no food, then a day of normal eating — did a little better than people who simply cut calories.
How much better? About 1.3 kilograms, according to the researchers. That’s less than 3 pounds.
And the study’s own authors had set 2 kilograms — roughly 4.4 pounds — as the minimum difference that would matter for someone with obesity. The every-other-day group didn’t reach it.
So picture this: You fast or nearly fast every other day, for months, and your reward is less than 3 pounds more than you’d likely lose by simply trimming your portions. You’d have to really love the routine to call that a bargain.
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Nobody knows what happens after a year
Here’s the part the influencers skip. The trials in the BMJ review lasted anywhere from three weeks to a year, and the median was just 12 weeks. Most ran less than six months.
Cochrane found the same problem: Few trials have tracked people’s results over the long haul.
That matters, because losing weight for 12 weeks is easy. Keeping it off for 12 years is the hard part. A diet that can’t show it works over the long run hasn’t proven much.
Fasting also tells you when to eat, not what to eat. According to Johns Hopkins Medicine, stuffing your eating window with high-calorie food, or with much bigger portions than usual, will likely wipe out any benefit for your weight or your health.
In other words, eight hours of burgers and fries is still burgers and fries.
Don’t pay anybody to help you skip breakfast
The lead author of the Cochrane review, Luis Garegnani of the Universidad Hospital Italiano de Buenos Aires, said fasting may suit some people. But he added that “the current evidence doesn’t justify the enthusiasm we see on social media.”
That enthusiasm didn’t come from nowhere. The Cochrane team said much of fasting’s surge came from social media and lifestyle influencers, along with promises of quick weight loss and a revved-up metabolism.
The good news is, people are starting to catch on. In that same IFIC survey, only 16% of Americans said they trust social media influencers and bloggers for advice on what to eat, down from 27% in 2018.
And 79% said they struggle to figure out whom to believe, since nutrition guidance seems to change constantly.
Here’s my advice: Fasting is the one diet that should cost you less, not more. The clock on your kitchen wall is free. So is the timer on your phone.
You don’t need a subscription app, a “fasting support” powder or anyone’s coaching program to tell you when not to eat.
And think twice before buying any supplement that promises to make fasting easier or work better. Popular supplements don’t always do what they claim — scientists now suspect some popular supplements could hurt your aging brain.
If you need to lose serious weight, fasting probably isn’t the answer
If your doctor says you have real weight to lose for your health, it’s worth knowing what the alternatives can do.
In a major 68-week clinical trial published in the New England Journal of Medicine, adults taking the weight-loss drug semaglutide lost about 15% of their body weight on average. People on a placebo lost about 2.4%.
That’s a different league from anything fasting has shown. These drugs aren’t for everyone, and they aren’t cheap. But Wegovy and Zepbound are changing how Americans get health care, and they belong in the conversation with your doctor.
If you end up with a prescription, don’t pay more than you have to. You can compare prescription savings options here.
Who should skip fasting entirely
For most healthy adults, fasting is a reasonable experiment if it fits your schedule. Johns Hopkins says it can take two to four weeks to get used to, and you may feel hungry or cranky along the way.
But Johns Hopkins also says some people shouldn’t try it at all:
- Kids and teens. Anyone under 18.
- Pregnant or breastfeeding women. This isn’t the time to restrict food.
- Type 1 diabetics on insulin. There’s a concern that fasting could push their blood sugar to unsafe lows.
- Anyone who’s had an eating disorder. Rigid fasting schedules may set off or deepen unhealthy eating patterns.
Whoever you are, Johns Hopkins says to check with your doctor before you start.
The bottom line
Does fasting work? Yes — about as well as any other way of eating less. If skipping breakfast or closing the kitchen at 7 p.m. makes it easier for you to eat less, go for it.
But it’s not a metabolic miracle, and the science so far doesn’t show it is. The real secret to losing weight is the same boring one it’s always been: Eat a little less, eat a little better and stick with it for the long haul.
And whatever you do, don’t let anyone charge you for the privilege of not eating.
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