Michael Phelps is a former competitive swimmer who is arguably the greatest Olympian ever, having won 28 Olympic medals, 23 of which were Gold. During the 2008 Beijing Olympics, Phelps caused quite a stir with his sweep of 8 Gold medals and 7 world records. However aside from his swimming achievements, it was his diet that went viral at a time when social media was in its infancy. It was reported that Michael Phelps was eating up to 10,000 calories a day, and this ‘broke the internet’.
What caused Michael Phelps’ diet to go viral and what is its legacy?
Back in 2008 it’s arguable that the general public’s grasp of nutrition wasn’t as strong as it is now. Foods were put into 2 categories. They were either ‘clean’ or ‘dirty’. The criteria that was needed to be clean or dirty weren’t very clear. Generally fruits, vegetables, whole grains and lean meats were considered clean. Junk and fast foods were considered dirty. Some nutritionists at the time were trying to set people straight that categorizing foods like this wasn’t always helpful, but traditional thinking prevailed. For some people it was thought that ‘eating clean’ was all that mattered, and if you took even a small bite of a dirty food, for example a cookie, then your fat loss progress would be ruined.
So when news of Michael Phelps’ diet broke, it led to a lot of confusion. Here’s a guy who’s eating pizza, meatballs subs and energy drinks, but he’s ripped! He’s eating dirty foods but he’s in shape. How does that work? Even more so, he’s an Olympian. Arguably the greatest Olympian ever. So his performance didn’t suffer by any means.
The super sharing and virality of Phelps’ diet was likely an integral part in changing the way many people think about weight loss today. Before it was about clean and dirty foods. But knowing that Michael Phelps could eat up to 10,000 calories per day, a lot of them labelled as dirty calories, and burn them off as part of his intense swimming practice made many people realise that energy balance was they key. Weight loss wasn’t some complicated mystery. You didn’t need to purchase some fat loss secret someone was trying to sell on a YouTube ad. Being in a calorie deficit is what mattered.

And while Michael Phelps’ diet helped people understand that you could lose weight even while eating such a high number of calories, dieticians and nutritionists called for moderation. The downside to the virality of such gluttonous consumption was that some people would view Phelps’ diet and think, “Wait a minute. I can eat all that and still stay slim? Sign me up!” However unless your entire life revolved around eating, sleeping and swimming, it’s unlikely to work for you. To put things into perspective, sumo wrestlers eat up to 7,000 calories a day and have a vastly different body compositions to that of Michael Phelps.
As such Michael Phelp’s hypocaloric diet was positive depending on how it was interpreted. You could eat what you want and burn it off later IF you performed the necessary activity. Stuffing yourself with pizzas, milkshakes and burgers, and then going for a stroll in the park didn’t quite cut it. Charts that published the calorie expenditure of everyday exercise activities put things in perspective. For a 155 lbs person, 30 minutes of activity would burn the following amount of calories:
- Swimming, 216 calories
- Walking, 133 calories
- Ice skating, 252 calories
- Basketball, 288 calories
- Cross-country running, 316 calories
One gets the idea. Burning 10,000 calories will require a lot of activity! Ironically for some people, the extreme diet of Michael Phelps taught them the importance of moderation.

Michael Phelp’s diet also provided greater insight into how integral eating was in many sports. For sports in which athletes need to ‘make weight’ such as boxing or wrestling, it can be a gruelling process whereby they limit their calorie consumption to dangerous levels. For other sports such as strongman and bodybuilding, athletes need to eat large amounts of food regularly to ensure they get stronger and maintain their size.
A common theme for high performing athletes is the difficulty to transition to everyday life after spending the better part of their life living the athlete lifestyle. This doesn’t mean just being out of the spotlight and no longer being in a competitive environment. It also affects their diet. Athletes like Michael Phelps had to consume a huge amounts of calories to sustain their activity. But once they retire, their diet often remains the same and their activity levels aren’t able to keep up. This happened to Phelps, who gained 30lbs after retiring due to a combination of less activity without cutting down on his calories. Just one of the many factors of why fat loss can be difficult.
For other athletes such as NFL players, the opposite can happen. Offensive linemen often weigh over 300 lbs. Over the decades they have been getting bigger and bigger. And in order to maintain this size, they need to eat a lot. Some NFL players have opened up about the pressure to eat, talking about how they would get in trouble with management if they missed a meal and lost some weight. Taking medications to alleviate stomach pains at night shows the lengths these athletes have to go to maintain their enormous size.
But once they retire that pressure disappears. Without even monitoring their food intake and just eating as they’d like, former NFL athletes have lost up to 60lbs of weight and look totally different after a few months of retirement. It’s a stark contrast to those who continue eating like they are athletes without the corresponding activity.

The virality of Michael Phelps’ high calorie diet would also affect the world of social media. Competitive eating has been around for a while, with the first recorded pie eating tournament supposedly having taken place in Toronto in 1878. Athletes have also been eating lots of food way before the Michael Phelps diet was even a thing. But the media exposure of his diet and racking up of gold medals put his calorie count into the limelight. It seems no coincidence that soon after, you see calorie challenges as a genre of video appearing on YouTube. Today eating challenges or calories challenges are widespread on social media, perhaps gaining their inspiration in their early days from Michael Phelps. And one can take this a step further and posit that the hugely popular genre of Mukbang, where content creators eat food in front of an online audience, can partly attribute its emergence to the virality of popularity surrounding Phelps’ diet in 2008.