The documentary is available on the SBS website: Fat Vs Sugar
What was the experiment?
Identical twin brothers, who are both doctors, put their bodies on the line for this month long test. One ate a high carb,low fat diet. This consisted of bread, pasta, breakfast cereals, sweets, fizzy drinks, fruit and and vegetables. The other twin ate a high fat, low carb diet. This consisted of cheese, meat, eggs, cream, mayo etc… Calories weren't limited, so they could both eat as much as they like.
Along the way they carried out some tests.
This tested their skills working in the stock exchange.. They got a 5 minute lesson on the stock market, were then given $100,000 to play with and let loose on the market.
Result: The high fat brother seemed to struggle a bit and said he felt foggy and was struggling to remember things and process thoughts. This was put down to the fact that the brains most efficient form of fuel is glucose, and it can take some time, usually a week or two, on a low carb diet to get fat adapted, ie: start using fat efficiently as fuel. The high carb brother fared much better and made more money.
I think this test was a bit questionable. For one, the high fat brother was in England and the high carb brother in New York. What time of day was the test done? Quite possibly it was late at night in England which would explain the foggy head. Also, as neither of them were experienced in the stock market it was basically gambling at the end of the day, so being the winner didn't really prove much in the mental stakes.
This was a cycling test. After fasting for 12 hours the brothers were put on turbo trainers for an hour and pushed and hard by a cycling trainer. After the hour, they were refueled with some butter for the high fat brother, and glucose for the high sugar brother. There was the same number of calories in both. They then had a cycle sprint race up a hill. The glucose brother kicked ass here.
This wasn't too surprising. Glucose is the primary energy source for our muscles in high intensity exercise. Fat is a better energy source for longer, low intensity exercise.
At the end of the month they were weighed and their body fat was measured. High carb brother lost 1 kilo of body weight, with half of that being from fat and the other half lean body mass. High fat brother lost a whopping 3.5 kilos, 1.5 kilos from fat and 2 kilos from lean body mass.
Cholesterol: Both of the twins cholesterol measured the same as before this experiment began.
Insulin: I am not going to give my opinion on the what happened here in the program. I would need to do some more research first. But it seemed a bit sketchy...
How come they both lost weight when they were both on such bad diets and not calorie restricted?
People will always lose weight when they are on any kind of restriction diet. You become more aware of what you are eating and whats in what you are eating.
The more I think about it, the more it looks to me like this documentary was well biased in the favour of sugar. The cycle sprint test was always going to be won by the sugar guy. I don't think anyone is arguing that fat is a better fuel source for short/high intensity exercise. The mental test was a bit shoddy in my opinion, as I already stated above. And when they weighed in at the end, even though the high fat brother lost more weight (3.5 kilos), the doctor was basically making it sound like a negative thing as he said he lost 2 kilos of muscle, and this could be detrimental to his health. But I don't see how he could say that much muscle. The Bod Pod can only measure body fat %, and the rest of your body is lean body mass. Lean body mass is not just muscle, it is everything in your body except for fat(bones, muscle, water, internal organs, blood etc..). It is unlikely that he lost any bone or internal organs during the test, so the 2 kilos would have been a mixture of muscle and water. When on a low carb diet it is very common the lose a couple of kilos of water weight quickly. As your glycogen depletes so does the water stored with it. This is why people get excited when they are on low carb diets for a day or two and drop a kilo.
I think the diets were too extreme to answer any questions properly. I would have liked to have seen it done in a way to try and figure out what are the optimal ratios of the macronutritnets, rather than completely cutting out one macronutrient. But I suppose that wouldn't make good television. I did find the piece about the rats interesting: when they gave the rats high sugar foods only they didn't gain much weight. When they gave them high fat foods they gained a bit of weight, but not much. But when they gave them foods half fat and half sugar, they ate a lot more of this food and gained a lot of weight. Its this delicious combination of high sugar & fat foods (ice cream, donuts, cheesecake) that are dangerous, as it would be pretty hard to over eat on pure sugar or fat.
Take away points
A well balanced diet of unprocessed meat, fruit & Veg, and regular exercise seems to be the way to go. And stay away from high fat sugar processed foods like cheesecake and donuts. Who would have thought!