[Phantasm]

I agree with those that say hobbits being overweight and apparently gluttonous is a result of their sedentary lifestyle with plenty of available food. Every town has a butcher, too, by all accounts, so they have cattle and pigs for draft and eating, no doubt (although the Nelwyns in Willow were not specifically hobbits, they're the same basic idea, and the title character there used pigs to pull his plow). I wouldn't put it past hobbits to have four-field crop rotation, either.

The books say "six meals a day, when they could get it." That last phrase is key: "when they could get it." They're not required to be constantly eating. Pippin, being the son of a very wealthy hobbit himself - Frodo, Merry, and Pippin were all Wealthy if not Very Wealthy or even Filthy Rich, by hobbit standards - and heir to the only hereditary title inside the Shire (the Thane) is used to having many meals. "Breakfast, second breakfast, luncheon, afternoon tea, dinner, and second dinner (supper)" make sense for the six meals; "elevenses" was added in the movies to make it seem like they had a meal every two hours in the average day: breakfast at seven, second breakfast at nine, elevenses at eleven, luncheon at one, afternoon tea at three, dinner at five, supper at seven. I wouldn't put it past such a well-to-do hobbit family to have a separate "dessert" at nine in the evening, either, before going to bed, making it eight distinct meals.

As for Sam, he appears to be stronger than the typical hobbit, though we don't see it until they hit Mordor. He carried Frodo for several days across the plains to Mount Doom, IIRC. Then again, he was a hobbit who was a field hand/hireling, for the most part, earning his living from Bilbo and later Frodo, so he was probably stronger due to working out more. In that sense, the live-action movie depiction can be believed to if we take him being larger as being more muscle than fat.