Lyle Mcdonald The Ultimate Diet 2.0

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.This causes changes inthe various neurochemicals stimulating a number of negative adaptations.I want to note thatthe response is not immediate, there is a lag time between the changes in all of these hormonesand the body's response.But that's not all.There are also many other adaptations which occur when you diet, so let's look at some ofthose.First and foremost, the drop in leptin directly affects liver, skeletal muscle and fat cellmetabolism, mostly for the worse.While the drop in insulin mentioned above causes better fat mobilization, it causes otherproblems.One is that testosterone will bind to sex-hormone binding globulin (SHBG) better,lowering free testosterone levels (this is in addition to the drop in total testosterone).As well,insulin is anti-catabolic to muscle, inhibiting muscle breakdown.The increase in cortisol thatoccurs with dieting enhances protein breakdown as well as stimulating the conversion of proteinto glucose in the liver.Additionally, a fall in energy state of the muscle impairs protein synthesis(although it increases fatty acid oxidation).The mechanism behind this is more detail than Iwant to get into here.But the combined effect of these processes is that protein synthesis isdecreased and breakdown is accelerated; this causes muscle loss.On top of that, high blood fatty acid levels tend to impair the uptake of T4 (inactivethyroid) into the liver.There are also changes in liver metabolism that impair the conversion ofT4 to T3 (active thyroid).Both of these processes cause decreased blood levels of T3.There issome evidence that high blood fatty acid levels causes tissues to become resistant to thyroidhormone itself (this is part of why just taking extra thyroid on a diet doesn't fix all of theproblems).After the initial increase, there is also a drop in nervous system output (that canoccur in as little as 3-4 days after you start a diet).Along with the drop in thyroid, insulin andleptin, this explains a majority of the metabolic slowdown that occurs.The change in livermetabolism (and the reduction in insulin) also impairs the production of IGF-1 from GH.All of these adaptations serve two main purposes.The first is to slow the rate of fat loss,as this will ensure your survival as long as possible.Related to that, the body tends to shut downcalorically costly activities.This includes protein synthesis, reproduction and immune function;there's little point keeping any of these functioning when you're starving to death.The drop inleptin, and the changes in hormones that occur are a huge part of why men tend to lose their sexdrive (and ability) and women lose their period when they get lean/diet hard.The second is to prime your body to put fat back on at an accelerated rate when caloriesbecome available again.Decreased metabolic rate and fat burning, along with improved caloricPage 24http://www.bodyrecomposition.comstorage all conspire to put the fat back on when you start eating again.As I mentioned earlier,this makes perfect evolutionary sense, even if it presents a huge pain in the ass to us.I haven't even mentioned the hunger and appetite issue which is a topic worthy of anentire book.The combination signal sent by leptin, ghrelin, insulin, glucose, and a host of otherhormones (cholecystokinin, glucagon-like peptide 1 and 2, bombesin and many many others) areall involved in both hunger and appetite.The changes that occur with dieting tend to make bothshoot through the roof: you tend to get and stay hungry, thinking about food nearly constantly.Bodybuilders and athletes may have unbelievable food control but it still sucks being hungryconstantly when you try to diet.Ok, enough about dieting, what about overfeeding?OverfeedingTo a great degree, most of the adaptations that occur with dieting reverse when youovereat.Actually, that depends a lot on the situation.As I mentioned above, the body as a wholetends to defend against underfeeding better than it does against overfeeding which is why it'sgenerally easier to gain weight than to lose it.Studies where leptin has been increased abovenormal (i.e.to try and cause weight loss in overweight individuals) have generally borne this out:except at massive doses, raising leptin above normal does very little.There are a couple of theories as to why this might be the case.One theory is that normalleptin levels send essentially a 100% signal, that is they tell the body that all systems arenormal.It should seem clear that raising leptin above 100% isn't going to do much.Anotherpossibility is related to something I alluded to above: leptin sensitivity and resistance [ Pobierz całość w formacie PDF ]

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