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comment by darkdantedevil
darkdantedevil  ·  2046 days ago  ·  link  ·    ·  parent  ·  post: Short-term fasting may improve health

" Also, I am sure that 2000 calories of steak isn't the same as 2000 calories of rice, or 2000 calories of soda."

Well, that depends on what you mean. The soda probably would not be very satiating, and you're probably be hungrier. It does not have the protein of the steak, nor the fiber of the rice. But weight-gain wise, you'd gain or lose the same amount of weight so long as your total calorie consumption was identical.

It's just thermodynamics. A calorie is a unit of energy [Food calories are : the energy needed to raise the temperature of 1 kilogram of water through 1 °C], your body takes a certain amount of energy to do all its tasks, and the excess is laid down as fat, because fat is the most dense way of storing excess energy your body has. So, from a "fat-building" standpoint, 2000 calories is 2000 calories. Otherwise, they're pretty different.

Just for fun, let's look at the nutritional profiles you suggested: Rice: around 1570 grams of rice gives us 2000 calories, 41 grams of protein, 68% of your daily sodium ,etc.

http://imgur.com/Nd3kwLV

Steak: around 960 grams gets you to 2003 calories, with 244 grams of protein and 29% of your daily sodium.

http://i.imgur.com/HsVeBdA.gif

Soda: about 14 and 1/4 12oz cans of the syrup would get you to 1995 calories, with no protein, but 185% of your alloted carbs.

http://i.imgur.com/d8SGaCb.gif

mk  ·  2046 days ago  ·  link  ·

I'm not sure that is true. However, I admit that I know little about nutritional science. I am a physicist by training, and from that point of view, it is possible that different amounts of energy are required to release the energy stored in the different types of food. The total energy available in a theoretical sense would be the Gibbs free energy. I don't know if nutritionists use combustion or something else when determining the caloric density.

darkdantedevil  ·  2046 days ago  ·  link  ·

Well, I should have spoke with a little less certainty (not unusual). So I revoke that, apologies.

http://www.precisionnutrition.com/digesting-whole-vs-processed-foods

Mentions what you are talking about "the cost of extracting energy" if you will. That includes: calories from chewing, cutting, and digesting food through different pathways. This particular article cites proteins as taking around 20-30% of their caloric content, carbs taking 5-10, and fats between 0-3%.

That being said, this time I'll qualify this information appropriately, instead of being an ass. Human nutrition is a complicated field, and very VERY expensive to examine appropriately, because of all the variables at play.

I should not have said 2000 calories of anything will EXACTLY impact your body in the same way, but I think a revised statement might work. "Within a margin of 30%, any calorie will impact you the same way." You could either adjust your dietary calculations to account of this discrepancy, or, as most people do when they successfully manipulate their intake, just leave a wide enough margin (positive or negative) to absorb those differences and still achieve your desired net goal.

mk  ·  2046 days ago  ·  link  ·

Cool, thanks for the info. I'll bet that complicating the matter even more would be the influence of individual genetics, and possibly gut flora.

At any rate, I would suspect the a variation around 30% is a sound assumption.

Andy_B_Goode  ·  2044 days ago  ·  link  ·

If I'm not mistaken, all those considerations are taken into account when they calculate caloric information on labels. If the package says 100 kcal, that means that eating it will give your body 100 kcal to burn for fuel, build into muscle or store as fat. Obviously if you did something like convert the matter into energy direct by means of nuclear fusion you'd get a hell of a lot more than 100 kcal out of it, but the label is meant to be understood as the amount of net energy the average human body can extraxt from the product.

In terms of strictly weight gain and weight loss, a calorie is a calorie. In terms of general nutrition there are other considerations (which basically boil down to: eat lots of vegetables and lean sources of protein, and get your carbs from foods that are high in fiber), but the number on the scale will directly correspond to the number on the nutritional information.