 What accounts for the thermogenic effect of nuts, their purported ability to boost metabolism, such that one could potentially burn more fat just sleeping or sitting around? An explanation for this rise of resting energy expenditure is not obvious. The Texas A&M folks thought it was the arginine, but others recently suggested it may be a function of the flavonoid phytonutrients in nuts. Based on what kind of evidence? Studies like this. The effects of concord grape juice on appetite, diet, and body weight. Just as nuts are calorically dense yet don't seem to cause weight gain, welches was keeping their fingers crossed that the same would be found for purple grape juice. They had people guzzle down two cups a day for three months. Now, you gotta understand, welch's grape juice has more sugar than coca-cola. Two cups of purple grape juice contains the equivalent of 20 spoonfuls of sugar. The control group was basically given a grape kool-aid, a substitute grape-flavored drink, same number of calories, same amount of sugar, but just no detectable phytonutrients. So at two cups a day they were giving hundreds of extra calories a day to these people. Surely after three months they'd gain a couple pounds. What do you think they found? The grape-flavored sugar water group did indeed gain a significant amount of weight. How could they not with all that extra added sugar in their diet? But the grape juice people didn't. In fact, are you ready for this? Their waist circumference significantly shrank. They appeared to burn away significantly more tummy fat by drinking grape juice. So maybe there is something to the theory put forth by the nut-and-green tea people that flavonoid phytonutrients are capable of increasing thermogenesis, heat generation, and fat oxidation. If true, then it's just one more reason to eat nuts and drink green tea, not grape juice. Instead, eat Concord grapes.