I can confirm from personal experience, that Curt Schilling is exactly right:

On coming into next season in good shape …
“It’s not a diet, it’s a lifestyle change,” said Schilling, who said he woke up around 4:30 a.m. for a short run yesterday, and ran again this morning. “You can’t diet. There’s just no chance of that happening.”

Schilling, who turns 41 years old today, will receive a bonus of up to $2 million if he meets goals at six different weigh-ins. He said he wasn’t sure when the first Red Sox weigh-in was, but he said the goals were doable

Diets are for suckers. You’re whole lifestyle has to change. My own favorite guide in this area is Walter Willett’s Eat, Drink and Be Healthy.