Are you losing fat or fluids if you diet and drink alot?

A friend is on an extreme diet that includes acupuncture (amongst other) - his diet is that 2 days he isn't eating anything (literally) and the rest he eats very little - up to twice a day, 1 portion chicken, 1 yogurt etc - He can drink (and should) drink every day - he claims he drinks as many as 3+ liters of water a day - and still lost 6 kilos in the past 2 weeks.

My question: Did he lose fluids? or actual fat? (carb->>energy etc.etc.)

If you drink so much a day, and still lose weight, is that also fluid drop?

p.s. - he is not a tall person, and original weight is 110Ks. (more a chubby person than fat)

He did lose 2 belt holes, and looks thinner in his face.

EDIT sep-16-2012: Not sure why you think this Q is off topic, but I will still update: Current loss weight stands at 9KG - He still holds this formula. I think he will 'lose' all that he lost once he starts living though.

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Hard to tell, would need to do a body composition comparison. There's a third option though - muscle loss. – Robin Ashe Aug 15 '12 at 13:22
Do you have a question that relates it to your own workouts and goals? As it stands, this is off topic for the site. – JohnP Aug 15 '12 at 15:10

If you know how tall he is, you could do some calculations. This site calculates the basal metabolic rate, given weight, height and age.

A 30yr old male of 110kg and height of 1.8 m, will have a BMR of 9500kJ/day. (The formula is just an approximation, and actual BMR will depend on many other factors)

Next, note that 1kg of Fat stores 37000kJ of energy. This means that in order to lose 1kg of fat, the 30yr old man above would have to fast for 37000/9500 = 3.9 days. After two weeks of fasting, he would lose (14*9500)/37000 = 3.5kg. This is if he was not eating anything at all for 2 weeks and doing no exercise. If he were to exercise in addition, he could possibly lose 7kg of fat in the two week period.

In your scenario the man is only fasting 2 days a week. I therefore think it is unlikely he would have lost 6kg of fat in the two week period. In the above example, if protein was burnt instead of fat, he could have lost 14kg of protein, since 1kg of protein stores half the energy content that 1kg of fat stores.

Therefore I assume his weight loss could be attributed to a combination water, fat and protein, but not all to fat. Also body weight varies throughout the day, so perhaps he did not weigh himself at the same time of the day when he calculated his 6kg loss.

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+1 I think this is a good analysis that proves that all of the weight loss could not be fat. But, it does not work in the other direction; just because you are fasting doesn't mean you will lose your BMR in fat or muscle. – michael Sep 16 '12 at 23:45

Carbohydrates attach to and retain water, so when your glycogen stores are reduced from alow carb diet, there is accompanying water weight loss imperfect citation here. This is often responsible for early, fast weight loss of up to 10 lbs. This rate of weight loss is not sustainable because once glycogen is depleted, the effect stops. The water extra water that the person drinks can not be retained because it has to attach to some other molecule to avoid being flushed out.

On the other hand, the diet you are describing sounds like a starvation diet, which might cause significant weight loss, and might also cause health problems.

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Just with regards to two days a week of no eating. While starvation diets could cause health problems, it is also possible that intermittent fasting could prolong lifespan:en.wikipedia.org/wiki/Intermittent_fasting – Mew Sep 17 '12 at 9:10
@Chris There's pretty flimsy evidence of that, and recent results from primate studies show that calorie restriction does not extend lifespan: nytimes.com/2012/08/30/science/… – michael Sep 17 '12 at 13:35
x2, as many of the early studies on IF (intermittent fasting) were done on rats, and did not take into account overall health/condition. While it may work for some people, it may not for others. Finally, in the human studies, it was done as a method of weight control, not longevity, and it's been proven that obesity is a life shortening condition, so anything that reverses it would naturally prolong the subjects expected lifespan. – JohnP Sep 18 '12 at 14:52
@JohnP Obesity may predict a shorter life expectancy, but it's a jump to say that reducing obesity would lengthen it. Science is littered with the corpses of that type of assumption. And, of course, there are no diets that have been proven to cause long term sustainable weight-loss, so it's a moot point. – michael Sep 18 '12 at 15:23
@michael - It's a causal assumption true, but that should be somewhat self evident anyway. – JohnP Sep 18 '12 at 16:46