Lewis Hamilton had to go on an 'extreme diet' after the summer break. Here is why F1 drivers have to meet an exact weight.

• Lewis Hamilton returned from his F1 summer vacation about seven pounds overweight.
• Teams require their drivers to meet an exact weight requirement to improve the car's performance.

Who hasn't eaten a bit too much while on vacation?

Lewis Hamilton proved he is just like us when he overindulged during F1's summer break and had to go on what he called an "extreme diet" to return to his required racing weight when the season resumed.

Before the Dutch Grand Prix, Hamilton was asked about his summer vacation. He revealed that he spent part of the nearly month-long F1 summer break in the US playing with young relatives.

"I did some hiking in the mountains [near Los Angeles], and then I had a real unplugged rest in the sun, so I got a really good tan," Hamilton told the media. "Otherwise, just competing with my niece and nephew every day — running and jumping in the ocean. My niece, she just wants to do cannonball all of the time."

Hamilton, who is a vegan, also said he ate too much.

"I ate so much food," Hamilton said. "My weight has to be around 73, 74 kilos, and I was almost 77 kilos on Saturday. I was like, 'Oh God!' so I had to go on an extreme diet these past days."

As Hamilton noted, he has a strict weight window of 73-74 kilograms (about 161-163 pounds), and he had to shed at least three kilograms (or seven pounds) in about five days.

Carrying extra weight slows the car down, so teams want their drivers as light as possible. That means the drivers are pushed to land at or below Formula One's 80 kilograms (176 pounds) minimum weight for drivers. That includes the gear they wear in the car, which weighs approximately seven kilograms (15 pounds) and means the drivers' actual minimum weight is about 73 kilograms (161 pounds; if they go under, ballasts are added to the cockpit to reach the minimum).

A single kilogram can mean a huge difference in races where teams constantly look to shave tenths-of-a-second off times.

"Ten kilos of fuel in the car costs three-tenths of a second every circuit, per lap," Hamilton told Graham Norton in 2019. "So if I'm one kilo overweight, I can lose up to two seconds in the race distance. So my weight is very important."

To make matters more complicated, drivers still need to be strong. While the weight requirements limit the amount of muscle some can have, they must also be conscious of how that muscle impacts the car's performance. Hamilton says he must adjust his body to be lean instead of bulky, and the weights he does are designed to keep the center of his mass as low as possible.

"You have to have really good core stability," Hamilton told Norton. "You can't be big and bulky. If I was super-muscly [in my shoulders], my weight would be too high [vertically]. So, I do lots of squats for my butt."

The F1 weight issue has improved

Things were even worse before F1 raised the minimum weight in 2019.

Alfa Romeo driver and Hamilton's former Mercedes teammate Valtteri Bottas said earlier this year that he believed he had developed an eating disorder earlier in his career to maintain a team-mandated weight of 150 pounds.

"I trained myself to pain, physically and mentally," Bottas told Maria Veitola during an interview in his native Finland. "It got out of hand, and it became an addiction. No eating disorder was officially diagnosed, but it was definitely there."

Bottas says he would only eat steamed broccoli between long workouts and hid his diet choices from his team.

"It wasn't very healthy," Bottas said. "I wanted to be the best, and I thought I had to do that. If the team says that I have to weigh 68 kilos (150 pounds) and I naturally weigh 73 kilos (161 pounds), then they will do everything for that."

Bottas has a listed height of 5-foot-8. Things get even tougher for taller drivers, like Williams driver Alex Albon, who is 6-foot-2, or naturally bigger. In 2014, the 6-foot-tall Niko Hulkenberg, who now drives for Haas, weighed 165 pounds (75 kg) and was reportedly not considered for the open seat at McLaren because of his size.

"Heavier drivers will be less attractive," then-McLaren CEO Martin Whitmarsh told Sky Sports in 2013. "It has happened by accident. We have raised the minimum weight, but the new powertrains are heavier than people expected, and now have a situation where heavier drivers could be a disadvantage."

Bottas did say that the new weight minimum has helped, noting that his health immediately improved.

"I think the regulation is good, especially for the taller drivers," Bottas said in 2019. "It makes life a bit easier. Many drivers had to be below our natural weight, and it is very easy to get ill or sick. This is the first winter for many years that I didn't get any flu or any sickness."

It may be better, but as Hamilton has shown, it can still be a problem.