I've just been watching a BBC Horzions documentary on the Atkin's Diet in which they made the rather extravagant claim that the fact that the diet works contravenes the first law of thermodynamics -- that it contradicts the idea that energy can neither be created nor destroyed. They had some chemistry academics on the programme "explaining" how this is so. The narrator said that food was energy and one of the chemists burnt a sugary pastry that he had soaked in liquid oxygen to show how much energy there was in food. He then said that the energy from the food either went towards doing something with your metabolism or that it ended up as fat on your body. Surely this is nonsense. Why do they claim that the amount of energy you consume is the sole indicator of how much weight you will gain? Surely it's the actual quantity of substance that is retained by your body that will dictate how much weight you will gain. Why must your body take all the energy from the food? Aren't there circumstances which might mean that your body actually wastes some of the energy that you consume, and will hence not store it as fat? The reasoning presented in the programme to support the claim seemed to be rather specious to me.
Sure, when you have a shit, that's wasted energy. Also Fat contains more energy than say sugar per unit weight. So If your body requires only say 100 units of energy a day, and you eat 20 grams of fat which contains 10 Units/gram energy, then your body will stor 10 grams of that fat to use at a later time. If you keep eating 20 grams of fat a day, you will put on weight. On the other hand if you eat 20 grams of sugar that contains say 5 Units/gram, then you will not put on weight. It may seem inconvenient in todays western society where high energy dense foods are readily available, but this mechanism would have had an evolutionary advantage in our past by allowing us to store energy in our body instead of having to continually eat.
On the other hand if you eat 20 grams of sugar that contains say 5 Units/gram, then you will not put on weight. If you do not "burn"(excercise etc) that energy you will put on weight!
You did not read the post correctly. The presumption is that we require 100 units of energy a day. ANYTHING we consume over this will either be excreted or stored for future use. Also note this. In its daily activities, the brain uses approximately 20% of the bodies total energy requirements. Further the brain uses only sugars as energy sources, no fats, proteins or fibres. Thus the sugar craving at about 3:00 in the afternoon.
Energy basically comes from the ATP. Most of the material that is in food is used to reconstruct dead tissue. Excrement is unused and unstored food in part, but it is also discarded tissue. From what I've heard, the Atkins diet is based on the idea that your body can only catabolize so fast, which includes energy consumption and fuel storage. So, if you eat at a rate that exceeds your catabolism, then you won't put on any extra weight for the extra food that you eat. The emphasis is of course to not eat carbohydrates, because these have a high catabolic rate. At best, this seems like a very misguided and wasteful diet to me.
The programme then went on to say that the reason that the Atkin's diet works is because the people who are on it actually do consume less food than other people. The diet supposedly makes you feel less hungry. So all that stuff about it apparently contravening the first law of thermodynamics was just sensationalistic nonsense designed to keep you watching for the entire hour it took them to say that little bit I said above. I started this thread about halfway through the programme.
There are other less obvious energies involved as well, such as oxygen, and other air particles etc. Also sunlight is absorbed and other sources of heat etc. I am quite confident however that staying in the sunlight isn't going to create a gain in weight, not directly any way but may act as a catalyst that effects the metabolic rate in other ways. I think it is way to pragmatic to think of food as the only area of concern. This being the main reason that we don't have any really successful diets or understanding of metabiolic rates etc. Why can I eat anything I want to and not put on weight and yet some one else with the same diet does? Eat the same, shit the same but weight gain is different?
I would have thought there was very very little energy wasted in shit! Our bodies are designed to make the most of what we get to eat and its ability to convert food to energy or storage can change depending on our circumstances. It is usually impossible to eat more than the upper limit of this conversion because our brain sends a signal telling us to stop eating!
There are huge amounts of energy wasted in excrements. But then the whole food chain implies a huge amount of wasted enerygy. Only plants and some uni-cellular beings can capt energy from the sun throught catabolism to fuel the construction of their cels. But even then, all the plants on the surface of the earth only conserve 2 to 3% of all the energy that the earth receives from the sun. Animals and other beings that do not get their energy from the sun are a bit more efficient, capting 10 to 25% of the energy they consume. But that still means that for an animal that is relatively high in the food chain, there is a very large amount of wated energy. For example, to make an eagle gain on gram of mass, you need many kilograms of grain to feed the mouse that will feed the snake that will feed the eagle.
Well, rather than making the subject of this thread about excrement, the main thing I had in mind was attacking BBC sensationalism.
The entire point of the Atkins diet is that you eat lots of lean protein rather than lipids or carbohydrates. Protein-rich foods relieve hunger much faster than carbohydrate-rich foods; you can eat 300 calories worth of meat and feel like you've had a good meal, while 300 calories worth of carbohydrates would probably leave you feeling hungry. The idea is to allow you to cut back on your calorie intake without leaving you hungry all the time.
I don't think this is correct. Foods high in Carbohydrates necessarily contain sugars which are released into your blood stream to be used by cells to produce ATP. As blood sugar levels increase, the body will release insulin in an effort to keep blood sugar levels relativly constant. However the theory is that insulin prohibits the body in metabolising fats and so any fats ingested are stored and not burnt. A diet high in fat and protein reduces the amount of insulin the body produces and thus fats are more easily metabolised
I think they have found the real reason people lose weight on the Atkin's diet. Because they burn an extra 1200 calories per day by yapping to everybody and their brother about how they're on the "Atkin's diet".
Don't forget breathing. You exhale more mass than you inhale. The difference depends directly on how much energy you burn.
The point of the diet is that the body switches from glycogen to ketones for energy. When you have high bloodsugar there will also be alot of insulin in the blood, and insulin stores fat. You don't want this if you're on a diet! When blood-sugar is low glucagon will be released for the liver to secrete some of it's stored up glycogen. Glucagon also does to fat contrary to what insulin does, it releases the bodyfat to the bloodstreams as free fatty-acids, which can the be converted into ketones by the liver. Now this is an ideal state to be in to lose bodyfat. I also read that ketones are the 25% percent more efficient fuel for the brain, but I have no idea if that's true. Actually I'm on a Targeted Ketogenic Diet right now, as I need to lose some of the fat I've earned weightlifting Please Register or Log in to view the hidden image! Targeted means that I eat some carbs only before I train. A
Atkins said that his diet works because carbohydrates end up as sugar in the blood stream, cause insulin to be released, and that fat storage cannot occur without insulin. It's not a conservation of energy issue, it's a fat storage issue, and the fact that a TV special would be produced about the Atkins Diet featuring scientists who didn't understand the idea of the Atkins Diet is astounding. In fact there was a large independent study recently, which unfortunately I cannot easily cite, in which it was shown that people on a low fat diet lost less weight than people on a relatively low carb diet, consuming precisely the same number of calories a day. I do remember that in this particular study, the researchers both prepared the food and watched the people eat it to discourage cheating.
Simply put, insulin is an anabolic hormone which is released in times of plenty. It helps store fat so when insulin is low, even though you may be consuming many calories, the body thinks it is in a time of starvation and releases fatty acids. Anyway, this is biology really isn't it!
Go and talk about the mechanism behind the Atkin's diet in the biology forum. This thread was about the BBC's suspect claim that if Atkin's diet followers actually consumed more energy while losing weight they were violating the first law of thermodynamics. Anyway, the programme actually said at the end that people who followed the diet actually ate less than they would normally -- the diet makes them feel less hungry.
