 If phytonutrients can alter gut flora in a way that helps people lose weight, then you'd think people eating diets based on plants would have significantly different colon populations, and yes, indeed, that's something that's been known for four decades, and may help explain why those eating plant-based diets tend to be slimmer. Another reason vegetarian eating patterns have been tied to better weight management may be the water content of plant foods. Fruits and vegetables average about 80 to 90% water, just as fiber can bulk up the volume of foods without adding calories, so can water. Cognitive experiments have shown that people tend to eat a certain volume of food, and so when that volume is mostly water, they don't end up gaining as much weight. But even if you take out the visual component, instead just stick a tube down people's throats and feed them whatever volumes of food you want, if you add more water to their stomach, they tend to eat less. Perhaps because of the stretch receptors in their stomach, sending signals to the brain saying, we've had enough. Scientists have identified a multitude of ways our body controls our appetite, and a good thing, because if we were off just a few percent every day, that would have huge impacts on our weight over the years. If water is so helpful, why can't you just eat a steak with the glass of water? Doesn't work. You feel more full during the meal, but you end up eating the same amount of calories throughout the day, unless they found you preload. Drinking water with a meal doesn't seem to help control calories, but drinking a big glass of water a half an hour before a meal might. Thus it appears that water on its own may be effective at increasing satiety and decreasing intakes for some population groups when drunk before, but not with a meal. Ice water may be even better, or even just ice. Water has zero calories, ice has less than zero, since our bodies have to warm it up. From the annals of internal medicine, the ice diet, using simple thermodynamic calculations of how much heat our body would have to generate to take an ice cube up to body temperature, they conclude eating a quart of ice, like a really, really big snow cone with no syrup, could rob our body of more than 150 calories, the same amount of energy as the calorie expenditure and running for a mile. Sound too good to be true? Is actually, as Ray Cronyce talks about in his body hacking work with thermogenics, you may just be diverting some of the body's waste heat. If one really wants to use chronic mild cold stress to lose weight, turning down one's thermostat or wearing fewer layers outside may be more effective in the long run than drinking slushies of slush.