The klaxon sounded. For the next ten minutes, a row of men ate hot dog after hot dog with alarming speed, washing them down with swigs of water. One man stuffed his face faster than the others. The 37-year old Joey Chestnut managed 76 hot dogs, a new world record. His 2nd place rival ate just 50.

Chestnut is the Michael PhelpsAn American swimmer and the most successful Olympian of all time. of competitive eating. Since breaking the record for grilled cheese sandwiches in 2006 - he ate 47 in ten minutes - Chestnut has smashed a total of 51 other records.

But perhaps he should be more careful. A new University of Michigan study claims that eating a single hot dog shaves 36.3 minutes from your life expectancyThe number of years that a person can expect to live. . Chestnut's record attempt cost him two days. 

The study analysed over 5,800 foodstuffs. Some can extend your life: a peanut butter and jelly sandwich supposedly adds 33 minutes. A bowl of chips adds 90 seconds.

Some commentators were incredulous. If the study was accurate, tweeted sportswriter Gary Sheffield Jr: "Joey Chestnut would be dead already."

These doubts are understandable. From red wine to red meat, scientific reports on the nutritional quality of foodstuffs have been subject to dramatic flip-flops. "Sometimes I wonder," says medical journalist Clare Wilson, "if we should believe anything we read about food".

Take eggs, once viewed as benign sources of protein. But in the 1960s, scientists found that they contained an unhealthy amount of cholesterolA type of blood fat produced by the liver.. By the 2000s, eggs were back on the menu, after experiments found that they did not increase cholesterol levels as much as thought. A new study in 2019 argued the opposite.

Whole diets are subject to similar flips. In 2013, a paper claiming the Mediterranean diet cut the risk of heart disease by a third was widely promoted. Five years later the study was found to be horribly flawed. The same year, scientists found that the low-carb diets popular among the health conscious can shorten lives by up to four years. Vox asked: "could this be the beginning of the end of nutrition science."

At the heart of these rapid shifts is the difficulty of actually accessing food's nutritional quality. It is hard to find out what someone normally eats. If you know you are being monitored you are likely to make changes. If you are asked to stick to a particular new diet, it is unlikely that some of your old food habits will not remain. 

It is also tricky to extract a food's effects from a wider diet. If you ask someone to eat more fish, it is likely that they will eat less of something else. Food does not exist in a vacuum: someone who eats lots of avocados might be healthier than someone who does not, but they might also exercise more or live in an area with cleaner air.

And research can be deliberately misused. Food companies can, and do, spin even the vaguest reference to a health benefit to their own advantage.

Food for thought

Yes: Science has often been manipulated. Kellogg's claimed one of its cereals made children 20% more attentive but were found to have compared the effect of eating cereal with that of having just water for breakfast. Colgate claimed that 80% of dentists backed its toothpaste, while not mentioning that a similar number of dentists had also selected competitors.

No: The facts are the facts. What we have to learn is to read statistics carefully to understand what they show. Scientific research is vital to our understanding of the world. We should not condemn it.

Or... Scientists are usually responsible in their research, and present things to the best accuracy they can. It is when scientific research escapes from the lab and enters the public domain that it becomes distorted.

Key Words

Michael PhelpsAn American swimmer and the most successful Olympian of all time. - American former competitive swimmer and the most decorated Olympic athlete of all time. During the 2008 Beijing Olympics, he consumed 12,000 calories a day.

51 - Chestnut has eaten 32 Big Macs in 38 minutes 15 seconds, 165 pierogi in 8 minutes and 182 chicken wings in half an hour.

life expectancyThe number of years that a person can expect to live. - The age to which a person from a particular place and social group can expect to live, uncontrollable accidents aside. As of 2020, Japan had the highest average expectancy at 84.5 years and the Central African Republic the lowest at 52.8.

Peanut butter and jelly sandwich - A popular childhood food in the US. A 2002 survey found that the average American will eat 1,500 before leaving high school. 

Incredulous - Unable or unwilling to believe something.

Flip-flops - Originally used in the 17th Century to describe something that flaps or flops. It began to be used to describe a type of sandal in the 1960s.

cholesterolA type of blood fat produced by the liver. - A waxy substance found in food and human blood. Cholesterol helps us build healthy cells, but an excess level can cause heart disease. 

Mediterranean diet - A diet based on the olive oil, fruit and vegetable-rich foods of Southern Europe, popularised in the US in the 1980s. In 2013, UNESCO declared the diet part of the Cultural Heritage of Humanity.

Low-carb diets - Diets low in carbohydrates have been popular throughout history. They were even favourited by athletes in the Ancient Greek Olympics.

Spin - In politics, an attempt to control or influence information to present a particular message. A Spin Doctor is someone skilled at such activities.