I am seeing people get stuck on Robert Lustig's (and most nutritionists and other chemists') analysis of sugar as being the cause of obesity and diabetes and 'turning into fat.'
Clearly, this kind of thinking is misled. I think by now we have all seen many lay people (including myself!) countering Lustig's argument by saying 'I eat lots of sugar and I'm lean'.
However, this isn't enough for some people, who see Lustig's fancy presentations and molecular-level explanations of exactly how sugar is metabolized, and they just can't see it any other way, regardless of the whole-human-organism-level results.
So I have been wondering... Where is the chemistry that proves Lustig wrong? We have large quantities of anecdotal evidence that shows sugar doesn't turn to fat (30bad is a testimony to that) and we have dr barnard showing that people reverse diabetes on high carb diets, and dr mcdougall showing that people prevent heart disease on high carb diets... but what about someone showing the chemistry of why sugar does not in fact turn to fat? where is the chemistry that shows fructose is good for you? is there someone out there debunking lustig with actual chemical, molecular evidence that his theories are wrong?
Obviously I'm aware that sugar is good for me. But I need this information to help family members who are stuck in this line of thinking. Anything helps.
Sugar does turn into fat. He is right in that aspect. But the problem actually lies when you combine the effects of carbs, proteins and fats. This is a detailed explanation by our now retired member Adam:
"High blood sugar levels are always the reason for storing fat in the body. However high fat intakes are correlated with obesity for several reasons, especially in diabetes.
Overweight people, in general, do not just consume a high fat diet. They consume a diet that is high in all of the macronutrients. Invariably, because people consume animal products that are high in saturated fats, they consume not only high fat intakes but also high in protein. If they just consumed a high fat, high protein diet, the chances are they probably wouldn't have high blood sugar levels and therefore probably wouldn't get that fat. Probably the opposite infact. But as we know, low carb, high protein , high fat diets are difficult to stick to for a reason - they are diets that we evolved to consume when times were difficult, not out of preference but out of necessity to survive when there was nothing better to eat. Hence people who are overweight consume not just high protein and fat intakes, but also high carbohydrate intakes. But not carbohydrates per se - they consume foods that produce a high glycaemic response, and a high insulinaemic response.
Eating fat doesn't mean it will be stored as fat - unless there are high blood sugar levels. Since higher protein intakes reduce calorie requirements, and many high protein foods increase the insulinaemic response (insulin is an anabolic hormone) despite producing a low glycaemic response, and many high protein foods also increase cortisol production (which increases blood sugar levels) and since excess protein is broken down to glucose (and if it may not be needed for dietary energy if there is already enough carbohydrates in the diet, it will be converted to adipose tissue), the high protein foods, in the presence of a high carbohydrate sufficient diet may therefore increase blood sugar levels.
Since high GL, high II carbohydrate foods cause short-term hyperglycemic response, this mean that there is already a higher chance of high blood sugar levels when these two are combined together. But when you add fat on top, you have a situation where there may be reduced insulin sensitivity as a result, and high energy dense foods. If you don't have enough carbohydrates in the diet, fat will be oxidised for energy, which prevents it from causing the reduced insulin resistance and the need to store it as fat in the body. But if you have enough already, there is nothing to do with the dietary fat except store it as fat.
Diabetics typically consume the standard western diet. This is not just a high fat, or high protein or high fat diet. It is a high fat and high GL/II carbohydrate and high protein diet. They also usually consume caffeine, which increase blood sugar levels via cortisol, and often consume alcohol too.
It doesn't matter what diet someone is on, if they are gaining weight, their blood sugar levels are too high at some time across a 24 hour cycle, on a regular basis. Or at least they would be, if they weren't converting the sugar to glycogen and body fat. Diabetics have more trouble regulating blood sugar, and are more prone to store as body fat as a safety mechanism as a result.
Neither high carbohydrate, nor high protein, nor high fat diets alone will necessarily lead to weight gain. It is the combined effect that causes problems."
ohh! my favorite thing to talk about!! I'm taking biochem now so i'll try and break it down for you. I believe its all explained in the 801010 book as well(haven't read it in a while) I'm a dietetics major and interestingly enough my nutrition classes that focus on nutrition through the life stages etc all say sugar is BAD, that it causes OBESITY. My hard science classes speak the truth(weird how that works since they're all requirements for the same major, could be why there is so much misleading "information" out there)....
Every cell in the body runs on glucose. EVERY single brain cell runs on glucose as well. Fat doesn't contain a lot of O (maybe 1 or two molecules depending on they type of fatty acid) The structure of sugars contain a lot of carbon, a lot of H, and a lot of O, good for hydrating the body(H20), cellular respiration etc. Sugars also come in monosaccharides and disaccharides. Monosacharides being galactose(the singluar unit that makes up milk sugar and is the cause of lactose intolerance because it is utterly-pun intended- indigestible by humans), glucose and fructose. Disaccharides are sucrose, maltose(beer sugar) and lactose. Sucrose is found in starches and is broken into glucose. Fruit is the best option because our bodies are EFFICIENT machines. Its all about convenience and thats why you get such RAPID energy from fruit because the sugars are already in the form that the body needs/desires, so the sugar is absorbed right into the blood stream and doesn't have to be broken down by the body causing cells to use energy. That is why sugar, especially fruit sugar is GOOD, it doesn't stress the body out but uses less energy and GIVES the body energy as well so your body can heal itself or just run more efficiently as a whole.
This is why fat is "bad": 4kcal/g CHO, 4kcal/g pro, 9kcal/g fat. If you don't get your calories from sugar, they must come from fat. They don't come from protein because even high protein foods are usually also high in fat and fat has more kcal/g than protein. Also protein usually does not come in large quantities unless in powders(hence the whole scare about protein deficiencies). Fat doesn't have glucose in it. So the cells don't really want it. The functions for fat in the body are to coat cell neurons in myelin sheath(which is very important), to line organs and to make cell membranes which are lipid bilayers. That is why as children, we need more fat because we are still developing those vital parts of us, but as adults, we already have them and usually have excess fat. Besides using fat for those functions, only in times of glucose starvation will the body break down fat in the liver. The liver cells are the only ones in the entire body that can break down fat. So over eating fat/under eating sugar overworks the liver causing diseases/fatigue etc. Why would it make sense to starve yourself of glucose which every single body in the cell can utilize and instead rely on only one organ to provide energy for the whole body? it doesn't. The atkins diet is based on the theory that if you eat fat you will burn fat. This is true--> in that diet, they say don't eat carbs, leaving the body no choice but to burn fat leaving the people who follow that diet extremely fatigued, secretly binging on high carb foods while still trying to eat high fat to follow the diet causing diabetes (sigh) and the fat to be STORED because once the body has glucose, it uses it. On high fat, the liver has to feed all the muscles, the brain, the heart everything, not fair to the liver. The breakdown of fats releases 3 types of ketone molecules, 2 are used by the brain and heart for energy, the other is used to greate glucose by way of gluconeogenesis (occurs in the liver. The NORMAL/PREFERRED pathway is glycolysis which occurs with sugar metabolism and can occur in EVERY cell). Ketones are acidic and lower the blood pH resulting in higher chance of cancer and when the blood is in a lower pH range b/c the body is using fat as fuel, you get into ketosis which is an effect of type 1 & type 2 diabetes (and a high fat diet such as atkins). Your body will use what it can but long-term on a high fat diet, your body will be like "eeeenough" and possibly become ill with a disease.
My professor in a nutrition class said that a low-carb/high-fat diet can reverse coronary heart disease. Does this make sense absofruitly not, for all the reasons I said before and because fat thickens the blood because it doesn't dissolve in it and clogs arteries. (mini rant about my prof)
Some Raw foodists or other people choose to put their body in a state of ketosis by water fasting, because with an absence of carbs, your body will burn fat. Water fasting is diff than a high fat diet-induced ketosis because with a water fast, the body is only burning old fat and is not being burdened with new fat.
Ketosis can also occur during intense exercise which people actually want so they can burn fat, just eat sugar before and after and you will have energy to exercise and will keep the fat off.
Also if you just use common sense knowing that our bodies are 70% water, and fat is hydrophobic, then our organelles in our cells will not want to necessarily interact with it. what is hydrophilic? SUGAR! (higher ratio of C, H, and O)
Also think about all the different functions the body has to do every second. If every cell prefers glucose, then it will rarely store glucose. If by some reason it does, we have glycogen stores that can store about 2/3 a pound of glucose. (3500 kcal=pound so about 2,333 kcal can be stored) Then comes thermogenesis which is the process of heat. Since according to thermodynamics every conversion(which the cells do a lot of) releases a teensy bit of heat, your body will use any possible excess calories to make up for this heat loss. Therefore glucose is rarely stored. If a person who thrives on a 3000 glucose diet eats 9000 cals for a long ass time, then it will start to be stored, but who would do that? Also the body always wants to heal itself so it will try and use extra glucose cals to rid toxins (a good reason to eat fruit because its simple to digest and lets the body do just that)
I hope this helps :) let me know if you have more questions, I love talking about this.
Great answer, Celine! You now have a fan :o
I guess someone should probably update the FAQs with your answer, it's a very common question around here :)
" If every cell prefers glucose, then it will rarely store glucose. "
I thought the reason a lot of glucose/glycogen isn't stored in the body is because it isn't very efficient (ya know, 4 calories per g vs 9 cals per gram in fat). Of course, I'm not saying that glucose ISN'T the preferred molecule for a LOT of processes...just doubting that the reason WHY a lot of glucose isn't stored is because the cell eats the glucose too quickly.
yeah if it has to choose between glucose and fat, it will use the glucose which it prefers and store the fat which you're right would supply more calories in a desperate time. same thing just different angles to come at it.
I'm not saying the body cannot store glucose. It can, but it would rather use it than go through the process of storing it. If you eat a supreme excess of glucose, and the body has nothing to do with it (which is rare if you're active and alive) then it will be stored and if the glycogen "tank" overflows and the excess isn't burned off in thermogenesis, then it will be stored as fat, but there are a lot of steps because the body doesn't want to store its favorite fuel. And if it doooes get stored as fat, it wont be a lot. Fat on the other hand most of the time gets stored almost immediately (when eating a high carb diet) because the body has little need for it.
Sedentary people on this lifestyle are losing weight eating more calories than before, its because they are eating less fat/less animal products/less processed foods & more carbohydrates which are slimming foods because they hardly get stored as fat on the body.
hmm I'm actually learning about this next semester so I don't have a detailed answer right now but i can try-> since complex carbs and simple carbs take different times to digest, it could cause bloating. Also, the body uses water when digesting carbs so since fruit usually contains water, it is easy for the body but complex carbs are usually dryer and if water isn't consumed before a meal, the complex carbs will take water from the body and that could cause dehydration or bloating. I personally don't believe simple and complex carbs in tandem is the best idea (gas, bloating, stomach aches) but I doubt it will cause fat gain. Water, simple carbs, complex carbs is the best order for food combining.
Complex carbs on their own do not cause fat gain and simple carbs on their own do not cause fat gain, together they may cause discomfort but they will not cause fat gain (maybe weight gain because of bloating but once bloat goes down, weight goes down)
Thank you celine and others for your excellent assistance here! Right now we have great explanations as to why we are RIGHT about sugar. we can help even more people by giving an explanation rivaling Lustig's in complexity and detail as to why he is WRONG. When I am talking to my family about eating sugar and they say "but lustig says..." what part of his deep scientific analysis can I point to and say "that's where he's wrong"?
If you watch 'sugar: the bitter truth' https://www.youtube.com/watch?v=dBnniua6-oM from 57:45 to 1:04:25 you will see what I'm talking about. He offers a step by step analysis of every single teeny tiny chemical reaction that takes place between fructose consumption and fat gain. I am looking for an explanation of comparable depth to show how his analysis is wrong.
he does not mention, and gives no reason that the reactions he shows would occur any differently depending on the fat content of blood. is that where he's wrong? if so, why? what exactly changes? or is it something else entirely that makes his analysis irrelevant?