If someone tells you he or she had lost, say, five pounds, does it mean that this person had lost five pounds of extra fat? Not necessarily. Body weight is a total measure that consists of the mass of fat, bones, muscles, internal organs and various bodily fluids.
Zilch! - for a simple reason that all that weight loss resulted from expending nutrients, evacuating undigested food you had eaten the day before and losing water through sweat, urination and moisture in exhaled air. Total weight lost: five pounds, total fat lost: zero.
Here's another example. In hot weather, your body may be losing quite a bit of water sweating. You can also lose a lot of water when it is not hot - by taking diuretics. Under such circumstances, you may lose five pounds or even up to 10 pounds, while the amount of fat lost, just as in the previous example, would still be zero.
By the way, unscrupulous "dietitians" may sometimes use this effect to cheat their clients, telling them that this is how they can lose five pounds in a week. They may pose certain diuretics-laced drinks or cocktails as obesity medication to keep the patient happy about losing the hateful extra weight. Such weight loss remedies may often contain laxatives as well. This is a good way to go, since many obese individuals are regularly constipated and this method can certainly cause them to lose five pounds. So it is only natural that evacuating their bowels more often will lead to weight loss. However, don't be naive: the weight you lose this way has nothing to do with losing fat.
As we have explained before, one may often lose weight way faster than fat. A question then arises: can you lose five pounds "honestly", through losing fat alone? It all depends on the diet selected. The purpose of any remedial fat-loss diet is to create a negative energy balance and thus prompt the body to expend its own stores of fat.
For example, in order to maintain body weight level, energy intake through food must be equal to energy expenditures. For weight loss to occur, one needs to create a negative energy balance, that is, expend more energy than the body receives.
Diets may be classified as follows by the size of daily calorie intake they allow for:
1. Regular Diet owes its name to the fact that its allowed daily calorie intake roughly equals the body's daily requirement, 1,700-2,200 cal. With such a diet, the negative energy balance would amount to about 200-500 cal a day, so the body would lose weight slowly, in 20-50 grams daily increments.
2. Reduced Calorie Diet: daily intake of 1,200-1,500 cal, negative energy balance: 500-900 cal, daily fat loss: about 50-100 grams.
3. Rigid Diet: daily intake of 400-800 cal, negative energy balance: 1,400-1,800 cal, daily fat loss: up to 200 grams.
As a rule, regular diet is not particularly popular for weight loss purposes since the loss of fat would occur at a very slow rate - this would not cause you to lose five pounds in a week. Rigid diet would ensure the fastest rate of weight loss, but many find it quite painful. Hence the reduced calorie diet, as a compromise.
Quite apart stands the total fasting whereas the body receives no nutrients at all, only water. Total fasting is quite popular since it is easier to bear than the rigid diet and it is possible to lose five pounds quickly.
But let us ask ourselves a question here: did the entire weight loss occur on account of fat? Of course not! A fasting body expends very little energy, 1,800-2,000 cal daily at the maximum, which corresponds to the loss of about 200g of fat (the same as with the rigid diet).
Whatever other weight loss there is occurs through expending energy from other soft tissues. Some of the weight loss comes through reduction of muscle mass since the protein in the muscles is the only nutrient capable of being converted into glucose.
While fasting, the body is forced to use up muscle tissue to convert protein into glucose. Glucose would be needed to synthesize a catalyst for the Krebs Cycle, which is the main bodily process for producing energy. Body fat serves as fuel within the Krebs Cycle, but a catalyst (synthesized from glucose) is needed to burn that fuel.
Unfortunately, glucose gets expended, little by little, and thus needs to be replenished. Thus fasting offers yet another example whereas total weight loss exceeds the loss of fat. So, if you ever decide to fast, don't read too much into the quick weight loss and don't believe that this is how to lose five pounds in a week because you have not lost much fat.
Remember, the actual fat loss here would only amount to about 200g per day. Thus, we are in a good position now to answer that question we asked earlier: how fast can you reduce your weight "honestly", through losing fat alone? The answer should be 200g per day at the maximum. If you lose more than that, make sure you know what accounts for that difference.
To be sure, with the rigid diet the actual weight loss may at time exceed the theoretical 200g, which would mean that the body is "eating up" some of the soft tissue. In such a case one would need to revise daily rations to make sure that the body is getting enough carbohydrates to synthesize sufficient catalyst for the Krebs Cycle, rather than use the protein from its own soft tissues for that purpose.
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