Which diet is the most effective for weight loss?

This could be a historic day in Sweden. Today it became official. After over two years of work, a Swedish expert committee published their expert inquiry Dietary Treatment for Obesity (Google translated from Swedish).

This report from SBU (Swedish Council on Health Technology Assessment) is likely to be the basis for future dietary guidelines for obesity treatment within the Swedish health care system.

The health care system has for a long time given general advice to avoid fat and calories. A low-carbohydrate diet (such as LCHF) has often been dismissed as a fad diet lacking scientific foundation. The time has now come to update knowledge in this area.

According to SBU, the only clear difference among different dietary recommendations is seen during the first six months. Here a low-carbohydrate diet, such as LCHF, is clearly more effective than today’s conventional advice.

From fad diet to best in test.

Here are some more highlights from the report:

Health markers

In addition, health markers will improve on a low-carbohydrate diet, according to SBU. You’ll get:

…a greater increase in HDL cholesterol (“the good cholesterol”) without having any adverse affects on LDL cholesterol (“the bad cholesterol”). This applies to both the moderate low-carbohydrate intake of less than 40 percent of the total energy intake, as well as to the stricter low-carbohydrate diet, where carbohydrate intake is less than 20 percent of the total energy intake. In addition, the stricter low-carbohydrate diet will lead to improved glucose levels for individuals with obesity and diabetes, and to marginally decreased levels of triglycerides.

So, all important health markers improved or unchanged on a stricter low-carbohydrate diet. Just like an international review of all research in the area showed last year:

Systematic review and meta-analysis of clinical trials of the effects of low carbohydrate diets on cardiovascular risk factors

Long-term uncertainty

Long term, studies show no statistically significant differences among different diets, and the differences decrease with time. The SBU suggests that this is because of decreasing compliance with time. People simply tend to fall back to old habits.

The more studies we add, the better we can see the clear advantage of low-carbohydrate diets. Unfortunately SBU has excluded all studies examining both obese and overweight people. If you include studies on weight loss where overweight people are included – to get a greater scientific basis – a clear advantage for the low-carbohydrate diet was seen even after a year:

New Analysis: LCHF Best For Long-Term Weight and Health Markers

A well-designed study, which for the same reason as above, was dropped from the SBU report’s analysis, still showed a persistent advantage for the LCHF-like diet (Atkins) after two years, despite the difficulty with such long-term diet studies.

For the long-term effect, if you keep to a strict low-carbohydrate diet, there are only anecdotal reports on weight and cholesterol levels.

Physical activity

SBU also kills the idea that exercise plays an important roll in weight loss. Exercise may be very good for health, but:

Systematic reviews of the literature show that the addition of physical activity to a dietary intervention for individuals with obesity have, if any, a marginal effect on weight loss at the group level.

The effect of exercise on weight in studies is in other words marginal or non-existent. Just like you read about here.

Warnings against LCHF dismissed

There’s a great lack of knowledge today on what dietary guidelines are best for long-term health. We simply don’t know.

Recent cautions on low-carbohydrate diets are at best based on statistical associations derived from food questionnaires from people who didn’t (!) eat a low-carbohydrate diet. The SBU also dismisses these warnings:

Most of these studies suffer from major shortcomings, which make them difficult to interpret. The foremost shortcoming in these studies is that it’s often impossible to determine whether those with the lowest intake are knowingly eating a moderate low-carbohydrate diet for health reasons, or if they are high consumers of fast-food.

The breakdown of carbohydrates, fat and protein, which in such studies are imaginatively labeled “a low-carbohydrate diet” is usually very similar to the macronutrient distribution in a hamburger with fries and soda…

Towards the future

What will be the consequences of today’s report?

Advice on a low-carbohydrate diet is however very rare, if we look at the practice survey. It’s not clear how common it is to actively discourage patients from the strict low-carbohydrate diet. A low-carbohydrate diet, even the stricter form, will lead to a greater weight loss in the short term than the low-fat diet, and studies have indicated no adverse effects on blood lipids, provided that the weight stays low. One possible consequence of this report will therefore be an increased use of a strict low-carbohydrate diet for short-term weight reduction.

SBU will always express itself very carefully. But it can’t be said much clearer: It’s high time for the health care system to take seriously advice on LCHF for weight loss!

This is also interesting:

…it’s not possible to draw any conclusions about the relationship between a low-carbohydrate diet – regardless of fat content – and cardiovascular disease. Here we could apply the precautionary principle, and advise some restraint on saturated fat intake, as long as the documentation of the long-term effects are inadequate.

Many health care workers will no doubt (without any better reasons than preconceptions) be wary of dietary advice on more saturated fat. I was once scared of saturated fat myself.

I think that SBU is keeping a reasonable attitude here, as it isn’t even necessary to give advice on a lot of saturated fat for a low-carbohydrate diet. You can eat even a strict low-carbohydrate diet (such as LCHF) emphasizing unsaturated fats. This has been shown to be effective in studies:

It would be wonderful if the health care system started to apply the benefits of a low-carbohydrate diet, even before the outdated fear of butter has melted away everywhere.

The SBU-report Dietary Treatment for Obesity is a gigantic step towards more effective dietary guidelines within the health care system. This is a historic day in Sweden.

Media coverage

Today’s big news created quite a media frenzy in Sweden, here Google translated from Swedish:

More on the SBU report Dietary Treatment for Obesity:

More

LCHF for Beginners

Just a few examples of that today’s news could mean for more and more people: