Sumo diet

According to this website, here are the five main things that sumo wrestlers do to gain weight (these were also mentioned in the info they gave out at the tournament):

1. Skip breakfast. By depriving their bodies of food after eight hours of sleep, their metabolic rates stay low.

2. Exercise on an empty stomach. If their bodies have no food, their metabolic thermostats are turned down even lower to conserve fuel.

3. Take a nap after eating. The Sumo secret for gaining weight is that, after eating, they sleep for at least four hours.

4. Eat late in the day. Going to bed with full stomachs means that their bodies must respond to the huge flood of nutrients with a rush of insulin, forcing their bodies to store some of it in the cells as fat instead of in the muscles and organs as nutrients.

5. Always eat with others in a social atmosphere. According to leading researchers, a meal eaten with others can be at least 44 percent larger and with 30 percent more calories and fat.

So, the healthy practice would be to do the opposite of all of these, meaning eat three balanced meals at regular hours, eat something before you excersice, don't take long naps after you eat (except on Shabbos!), and eat some meals alone. Sounds like great advice.