The Ice Diet PremiseThe calorie is a measurement of heat energy which is defined as the amount of heat needed to raise the temperature of a gram of water one degree. In the case of solid ice, it also takes 80 calories to turn a gram of ice into liquid water.
Therefore, eating one gram of ice (0 degrees Celsius) will burn calories to heat it to body temperature (about 37 degrees Celsius), plus 80 calories for the actual melting process. Each gram of ice causes the expenditure of approximately 117 calories. Eating an ounce of ice therefore causes the burning of approximately 3,317 calories.
Considering that losing a pound of weight requires the burning of 3,500 Calories, this sounds like a pretty good deal, doesn't it?
Why the Ice Diet Doesn't WorkThe problem is that when talking about food, we're talking about Calories (capital C - also called a kilogram calorie) instead of calories (lowercase c - also called a gram calorie), resulting in:
1,000 calories = 1 CaloriePerforming the above calculations for kilogram Calories, we find that a single kilogram of ice consumed takes 117 calories. To reach the 3,500 Calories required to lose a pound of weight, it would be necessary to consume about 30 kilograms of ice. This equates to consuming about 66 pounds of ice to lose a single pound of weight.
Therefore, if you did everything else exactly the same, but consumed a pound of ice a day, you would lose a pound of weight every two months. Not exactly the most efficient diet plan.
There are some other issues to consider, which are more biological. For example, some of the thermal energy involved may not actually be a result of biochemical metabolic processes ... in other words, it may not really result in calories burned from the metabolic storehouse of energy.