The skeletal muscles have a capacity of about 300g of glycogen storage. That glycogen sits there in the muscles until it used for vigorous exercise, so that "sink" has no more capacity. The liver stores about 100g of glycogen, but this can be released to the blood stream when blood sugar is low – if it ever gets low enough in a person who is continually snacking. (Keep reading to end for some important facts on insulin’s effect on protein intake)
When these liver and muscle reservoirs are full, the body does not waste any incoming excess available energy (food). It is very efficient in using valuable fuel. Excess glucose is converted to fatty acids and stored in fat tissue.
We can see that, for a sedentary person, a meal containing starchy vegetables, sweet fruits or flour products or sugar (and particularly sugary drinks like cola or fruit juices), will be an excess of carbohydrates for them and will be stored as fat.
Some will say, "but I drink Diet Coke", artificially sweetened. Sorry, but the same thing applies – the pancreas responds to any sweetness as if it is receiving sugar and secretes insulin.
If we ingest too much carbohydrate in one meal, there will be an insulin rush,overshooting the required amount, lowering our blood glucose too much. Soon, you will feel hungry again. Think of the popular "Chinese meal", high in simple carbohydrates (white rice) and probably sugar (sweet and sour) followed by banana fritters with syrup.
The above problems are increased by alcohol. All digestion is stopped, until it is broken down in the liver.
Over time, many of us become immune to insulin because the pancreas becomes over-worked by a life-time of high carb meals, so we need to keep producing more and more insulin. Then, the body becomes less efficient in converting glucose to glycogen and, instead, stores it as fat. Carbohydrates, not fats, make you fat.
If most of your carbohydrate is being shunted off into fat reserves, a lot of your food intake is lost to you. But what about your fat reserves? Well, if your body is used to burning carbohydrate, which it will always burn first, when available, fat will not be utilised. Also, when insulin is present in the bloodstream (and that’s most of the time when a person is always snacking), our fat is not released into the blood.
In view of the foregoing, it is rather disingenuous of doctors and dieticians (and exercise instructors!) to tell their patients to "eat less and exercise more". Many obese people will tell you that they "hardly eat anything" and that is probably true. Then, as I’ve said before, exercise makes us hungry! So, while I believe that many people become overweight initially through greed (second helpings or huge portions), once they start becoming insulin resistant because of over-consumption of carbs, they are losing half of their food intake to their fat stores. Obesity may start as occasional over-indulgence, but it soon becomes a hormonal problem.
Protein also stimulates insulin secretion. It is digested to peptides and finally, amino acids, which are used for growth and repair of tissues. Despite what many bodybuilders may think, our requirements for protein are fairly modest, at somewhere between one and two grams per kilogram of body weight per day. So a 75kg athlete might need 100-150g per day. This doesn't require huge consumption of flesh because virtually all natural foods contain protein. Even fruits and vegetables contain 2-3 g of protein, which adds to our total for the day. Although these proteins are from plants, the liver can reassemble their amino acids to form proteins useful to us.
Proteins, like fats and carbohydrate, are chains of carbon, hydrogen and oxygen, but with a vital difference; there is a nitrogen molecule attached. If we ingest an excess of protein, the energy is not wasted. The amino acids are de-aminated in the liver i.e. the nitrogen molecule is removed and expelled in the urine. And what are we left with? A carbohydrate chain - and you know what's going to happen to that, if there is no room in the glycogen stores......... It will be stored as fat. So, the myth that "we can eat as much protein as we like, without getting fat" is untrue.
In a future post, I’ll discuss an enjoyable, proven diet that actually works for weight reduction and long-term, healthy maintenance of body weight.
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