The water content of plant foods may help explain why those eating plant-based diets are, on average, so slim. Can ice be thought of as having even “fewer” calories than water since the body has to warm it up?
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 been known for four decades, and may help explain why those eating such diets tend to be slimmer.
Another reason vegetarian eating patterns has been tied to better weight management may be the water content of plant foods. Fruits and vegetables average about 80 to 90 percent 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 and instead 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 too the brain saying we’ve had enough… Scientists have identified a multitude of ways your body controls your appetite, and a good thing, because if you’re off every day just by a few percent that could have huge impacts on your weight over the years.
If water is so helpful… why can't you just eat that steak and drink a glass of water. It doesn’t work. You feel more full during the meal, but you end up eating the same number of calories throughout the day, unless, they’ve found, you preload. Drinking water with the meal doesn’t seem to help control calories, but drinking a big glass of water a half 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, but 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 your body of more than 150 calories, the “same amount of energy as the calorie expenditure in running 1 mile.
Sound too good to be true? It is actually, as Ray Crow-nice 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.
To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring watch the above video. This is just an approximation of the audio contributed by Kerry Skinner.
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The reference to phytonutrients altering gut flora was an allusion to yesterday's video-of-the-day Tipping Firmicutes to Bacteroidetes. Not only is fiber also calorie-free, but one might think of it in the same snowcone "negative calorie" light, given the fermentation of fiber in our bowel into anti-obesity compounds (as well as anti-inflammatory, anti-cancer compounds). On Monday we'll continue with the obesity prevention theme with Diet vs. Exercise for Weight Loss, one of the videos I featured in my full 2012 presentation Uprooting the Leading Causes of Death.
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