My Question up for answer is based on the information below, is it correct to assume that Carbohydrates in a balanced diet do not significantly contribute to fat conversion and storage but instead wreak havoc on the homeostasis of the body increasing Fat cells and using the fat content of the diet to store in these cells while the glucose from carbs are used for immediate fuel. If this is true then would it not also be possible that a diet devoid of significant fat sources and high in carbohydrates (lets put aside the argument against refined carbs and sugars) but not high enough to encourage conversion be possible to maintain your weight level? I realize fats are a necessary part of diet but theoretically speaking would this be true...
I am asking because this was recently thrown in my face recently during a discussion where I recommended the article and this was the viewpoint of the person I was trying to explain the merits of the paleo diet and that excess carbs encourage weight gain..
The article is Gary Taubes NYT artcile titles "What if its all been a big fat lie?" which I'm sure everyone is familiar with, the exert starts here:
"Then in 1982, J.P. Flatt, a University of Massachusetts biochemist, published his research demonstrating that, in any normal diet, it is extremely rare for the human body to convert carbohydrates into body fat. This was then misinterpreted by the media and quite a few scientists to mean that eating carbohydrates, even to excess, could not make you fat -- which is not the case, Flatt says. But the misinterpretation developed a vigorous life of its own because it resonated with the notion that fat makes you fat and carbohydrates are harmless." http://www.nytimes.com/2002/07/07/magazine/what-if-it-s-all-been-a-big-fat-lie.html?pagewanted=6
I know GT says it was misinterpreted and I am trying to deduce how...
I read the article by Flatt, you can find it here: http://www.ajcn.org/content/61/4/952S.full.pdf
Basically the circumstances are extremely rare: "To induce substantial rates of carbohydrate conversion into fat, the body’s total glycogen stores must be considerably raised, from their usual 4-6 g/kg body wt to > 8-10 g/kg body wt. This requires deliberate and sustained ovenconsumption of large amounts of carbohydrates for 2-3 d "
A 90kg person then would need 900g of carbohydrates consumed daily? Which would be 3600 calories?? this cant be right? Does 1g of carb = 1g of glycogen? I am sure I am doing the math wrong.. Just curious at what # of calories from carbs would be needed to promote this RARE circumstance..
Does that also include the body stores of glucose at 500g which is 120g in the liver and the remainder in muscle tissue which would need replenishing?
I found the following article which shows in animals that there is a storage of carbs as fat for general information: http://chestofbooks.com/health/nutrition/Science/The-Conversion-Of-Carbohydrate-Into-Fat.html
Thanks for anyone who can help clear this up!
I did a poster for a bio class on this:
Most of the studies conducted in the past thirty years have found De Novo Lipogenesis (DNL, the making of fat from carbohydrates) to be a minor metabolic pathway. The work of Hellerstein epitomizes this. Three of his major studies found under 5 grams of fat is synthesized through DNL daily (Hellerstein 1996, Hellerstein 1999, Schwarz).
All of these studies were under three months in duration. Participants in a 1988 study synthesized 85 grams of fat per day (816 calories) during heavy carbohydrate feeding during a short period (Acheson) (that is to say under similar conditions to Hellerstein's studies). This study was designed to completely fill glycogen, giving excess glucose nowhere to go but through the DNL pathway. This maximized DNL to a degree previously unseen.
A studying using 2H2O isotopes for an extended period of time in order to account for the slow turn over rate of triglycerides found that DNL processes 20% of non-essential fatty acid or 10% of total fatty acid (Strawford). This is in normal men aged 19 to 51 years, BMI 19 to 25 who are consuming a normal diet. Their rate of DNL fat synthesis was 50 to 60 grams a day (540 calories).
The ability for DNL to be expressed as a major metabolic path is made readily evident by Acheson’s overfeeding studying. However, the conditions provided were far from normal. It involved drastic changes in diet and energy expenditures. While providing a valuable “black swan” model, it does not typify everyday DNL. Just because DNL can be a major pathway in the short-term in extreme conditions doesn’t mean it is one regularly.
The bulk of the studies conducted that measure the rate of DNL fat synthesis have found DNL to produce under 5 grams of fat a day. However, these studies did not go on for long enough to account for the slow turn overrate of triglycerides. Strawford’s study proceeded for six months and found over a ten fold increase in DNL rates over the typical past studies. When a process is found responsible for 10% of the total fatty acid synthesis, it is a major metabolic process.
However, the basis for this is only one well set up study. More studies need be conducted to prove that DNL is a major pathway. It would be especially interesting to study the rates of DNL in the pregnant and the pre-diabetic.
Also, keep in mind that there is a 7% ATP hit for converting glucose into glycogen, and a 25% hit to convert it into fat. So, even when you do convert it to fat, you can cut a 1/4 of the energy right off the top. If you're lifting weights regularly, you're heavily depleting glycogen stores and making room for carb intake.
We all know people who seem to only consume carbs and are not fat. Personally, I think the obesity epidemic is purely the result of fructose intake, and that starch intake simply isn't capable of producing overweight humans in these numbers.
It may be, however, that you don't store the carbs per se, but your body shifts to only burning them and the fat in the diet is then stored. This would be a far more efficient design, and evolution tends to favor that which is efficient for obvious reasons.
From what i have learned getting my degree this makes the most sense to me-in short- Carbohydrates cannot be converted into fat, and cannot make you fat, etc. You have a limited amount of glycogen storage,as we we all know. When that is full, from my understanding the carbohydrates taken in from that point on are burned. Because this is your primary source of energy. So any fat intake (if your glycogen storage is full), and i mean any, will automatically store as fat and will not be used as energy seeing that it is not the primary source. This is what makes you fat. So yes, If one consumes too many carbs, they have potential of gaining weight because of the intake of fat (its pretty difficult to have a diet without any fat, also not recommended). If one just consumed carbs and didnt have an ounce of fat in their diet, they wouldn't gain weight. This is why you see people who have a high carb diet, maintain their weight, fitness levels...etc. So the real reason why 'cutting carbs' works and is recommended, is because your body starts to use the extra fat being stored as energy rather then using the carbs. People think they are cutting carbs because they are harmful, which is not true.
unfortunately, the standard vegan diet consists of a large amount of nut butters, coconut oil, avocados. Fat is very easily stored as fat, and it is 10 x harder for the body to convert carbs into fat. The key is to limit the amount of oil and fat in our diet. The fat you eat is indeed the fat you wear; not the carbohydrates (if not in excess), and not the protein.
I would think that just by sheer virtue of the fact that carbs are converted to sugar, then excess sugar is stored as fat, that yes, carbs do convert to fat--but not directly. There are a few steps in between.
De Novo Lipogenesis and Gary Taubes 2 Answers
Muscle glycogen? 4 Answers
What's wrong with Taubes? 12 Answers