Cincinnati Bengals guard Bobbie Williams (63) looks on during football training camp July 29 in Georgetown, Ky. An analysis of league rosters shows the number of 300-pounders has risen dramatically over the decades.

Ten or 20 years ago, Nate Newton and William “The Refrigerator” Perry were on a short list of larger-than-life rarities in the NFL. The 300-plus-pound behemoths made headlines simply for existing. Their every move shook the field and made people take notice.

These days, though, players their size hardly make a dent. Such is life in the ever-expanding world of the NFL.

An analysis of league rosters shows the number of 300-pounders has risen dramatically over the decades: From a single player (Gene Ferguson of the Chargers) in 1970, to three in 1980, 94 in 1990, 301 in 2000 and 394 in 2009.

“Amazing, if you think about it,” said Michele Macedonio, who has worked as a nutritionist for the Cincinnati Bengals for most of the past decade, when told of that figure. “The question they have to ask is, ‘How big is big enough and when do we stop getting bigger and think more about getting stronger and healthier and better?”‘

Like workers in any competitive business, NFL linemen know what they have to do to keep their jobs, and in this case that means staying big. So, this August is once again littered with scenes of 300-pounders sweating through hot training camp practices. The dangers of the combination of heat, sweat and weight were brought to the fore in 2001, when 335-pound Korey Stringer died of heat stroke during camp. There haven’t been any heat-related deaths in the NFL since, which in turn has dulled the debate over whether the NFL is becoming an overweight league.

But the biggest players never forget the perilous edge they’re on. They live with it every day.

“It’s been a struggle, but it’s something you’ve got to work through,” said Redskins nose tackle Ma’ake Kemoeatu, who was in the 400-pound range last season when he tore his Achilles while playing with the Panthers.

A struggle how?

“Eating right, getting back in shape. I have a weakness — food. My weakness is a piece of steak,” Kemoeatu said.

There were 532 players in the 300-pound-plus club heading into the 2010 training camps. Certainly, it’s possible some use — or have used — performance-enhancing drugs and slipped through the NFL’s testing system to get to where they are. And some of this season’s weights may be inflated now that a bright light has been shined on products such as StarCaps — the banned weight-loss supplement that led to the suspensions of a handful of players.

For the most part, though, the big players come by their girth honestly and are forced to walk a tightrope.

They spend the offseason in the weight room, trying to build muscle to bring their weight up. They sweat through practices, sometimes in conditions that are not conducive to anyone, let alone a 300-pounder, running around in full pads. Then they eat. They often eat between 5,000 and 8,000 calories a day, much of it in training-table meals the teams try to make low-fat and healthy. The goal is to keep the weight on in a healthy way — if there is such a thing as a healthy 350-pound man — lest they be pushed around, either by a teammate in practice or another team’s player when games start for real.

Kris Jenkins of the New York Jets has been on the tightrope most of his life. He recently dropped 25 pounds, to get to 365, by going on a so-called “cookie diet,” in which he eats 90-calorie bites of something that looks like a muffin top and contains milk, soy, whole-wheat flour and other ingredients.

“It was something that I realized I got to the point that I wasn’t going to be able to stick around the game for too much longer if I didn’t take better care of myself,” Jenkins said, when asked what prompted the diet.