Prof. Fredrik Nyström - Endocrinology Research

Approval for a Low Carbohydrate and High Fat Diet

In 2008, SBU, the Swedish Council on Health Technology Assessment, dropped a bombshell. After a two-year long inquiry, reviewing 16,000 studies, the report “Dietary Treatment for Obesity” upends the conventional dietary guidelines for obese or diabetic people.

For a long time, the health care system has given the public advice to avoid fat, saturated fat in particular, and calories. A low-carb diet (LCHF – Low Carb High Fat, is actually a Swedish “invention”) has been dismissed as harmful, a humbug and as being a fad diet lacking any scientific basis.

The SUB report turns the current concepts upside down and advocates a low-carbohydrate, high-fat diet, as the most effective weapon against obesity.

Super Size Me

You may be aware of Morgan Spurlock's 2004 documentary Super Size Me, in which the American film-maker ate nothing but McDonald's food for a month. Lots of people are disgusted to see what happens to the 33-year-old's body as he accepts Super Size shake, after Super Size shake, and limits himself to 5,000 steps a day and are shocked as his liver becomes toxic, his cholesterol skyrockets and his libido sags.

At the University of Linköping, the Spurlock experience has being replicated under clinical conditions. In February 2011, seven healthy medical students in their early 20s spent weeks stuffing themselves with hamburgers, pizzas, milk shakes and 200g bacon breakfasts - all on the university's tab. A second group of subjects a year later repeated the experiment. Physical exercise was avoided. The study was the brainchild of Fredrik Nyström, doctor and associate professor at the university's department of internal medicine.

This kind of study would probably be out of the question for ethical reason in many countries. Everyone would get sued if the subjects afterwards didn't manage to get rid of their extra kilos. But in laidback Sweden, there were no problems clearing the experiment with the national ethical board. The one proviso Nyström added was that he would pull anyone out of the experiment if they increased their bodyweight by more than 15% - even if he or she was prepared to go on.

Most students struggled to eat the required number of calories a day. They were not confined to McDonalds food, they could choose their diet, so long as they meet the calorie target. To do so they had to resort to emergency tactics like drinking cream, or spoonfuls of olive oil, or coconut oil. Or eating fried chicken or double helpings of bacon and eggs or eating a lot of cheese. They had to find sources of calorie dense fat. That much food was expensive, but the University was paying.

The students complained about the lack of exercise. And they didn't like feeling full all the time.

Spurlock's doctor recommended that he stop the diet because of elevated liver enzymes. Nyström is puzzled about why Spurlock had such an extreme reaction, musing that he could perhaps have had an undiagnosed problem with his liver. Spurlock gained 11.1kg, a 13% increase in his body weight. Perhaps because the Swedish students could eat a high fat diet, without the carbohydrates that are served at McDonalds, their livers were able to cope with this extreme diet. None of the Swedish students had severe changes in their liver enzymes.

Interestingly, in the Swedish experiment, while the liver readings got steadily worse until the third week, they then took a turn for the better. The liver, it would seem, adapts. Cholesterol, meanwhile, was hardly affected.

Nyström found that people respond differently to this feeding routine. One student gained only 4.6kg and his cholesterol was lower at the end of the trial than at the beginning. That demonstrates how difficult it is to change your cholesterol by changing your diet.

Students also showed a desirable pattern of lower blood triglycerides and higher HDL cholesterol. Many students added far less weight that calorie counting would predict. They seem to be "calorie resistant." On the other hand some students Added weight very quickly. One student was withdrawn after only two weeks having already gained 15% of his body weight.

A female student gained 9.1kg, close to 15% of her body weight. "I don't like what I see in the mirror, I look like I'm pregnant."

A male said the walking had become difficult. "I can't keep up with the guys, he complained. I walk 20 steps and I start to sweat. I've found that although I'm still interested in sex, i don't have the stamina to be as active as I'd like."

And this is the most fascinating thing: if Nyström's small group are representative, then it would seem that our bodies are more adaptable than we give them credit for. In other words, metabolism may play a much more important role in the problem of obesity than many people think. Indeed, Nyström claims that for some people, eating 10% more will lead to their metabolism increasing at the same level. The extra energy will be burned off as body heat during sleep. He also wonders if the cold Swedish climate encourages a metabolism that is good at converting excess calories into body heat.