This paper is an important one as it confirms the many studies from the last few years showing that low fat diets are not the optimal dietary intervention for long term weight loss. I agree entirely that it is high time that all groups offering weight loss advice move away from emphasising low fat. However what this paper also shows is that no approach is really all that effective when you compare results over a year. The difference between low fat and low carb was only a little over a kilogram - it’s not exactly impressive! I would like to stress that low fat and low carb are not the only options! So this is not a validation of low carb diets as some may interpret from the press release. What about one that is in the middle ground such as Mediterranean Diet or the newly studied Nordic diet? The study authors comments that we need to start looking beyond the distribution of protein, carbohydrate and fat are spot on - many other factors are much more important and a certain percentage of energy from fat or any other macronutrient is most unlikely to be the silver bullet to weight loss. We absolutely have to move towards a lifestyle change approach and one that emphasises real foods that satiate, while teaching good eating habits, adherence to appetite and satiety cues, as well as changing lifestyle behaviours including sedentary living, stress management, sleep and exercise.

The results are consistent with the Dietitians’ Association of Australia’s Obesity Guidelines, the NHMRC Australian Dietary Guidelines and weight management guidelines.  

More evidence to support what we already know. What really matters is that you restrict total energy (calories or kilojoules), not the macro-nutrient composition (total fat or carbohydrate).

Remembering that ‘diet quality’ is important for maximum long term health benefit, we need to consider the types and amounts of foods people eat.

What does this mean for Australians?

Over two thirds of Australian adults are overweight or obese which is likely to be due to too much food and too little exercise. In 2011-12, more men were overweight or obese than women (70% compared with 56%).

If current trends continue in Australia, it is estimated that by 2025, 83% of men and 75% of women aged 20 years or more will be overweight or obese.

Healthy weight is associated with reduced risk of chronic disease, including cardiovascular disease, type 2 diabetes and some cancers. Even small amounts of weight loss, 5% can reduce the risk of health problems like diabetes and cardiovascular disease.

Overweight and obesity contributed 7.5% of the burden of premature death and disability in Australia in 2003.

More recent data from Western Australia and Queensland indicate that overweight and obesity have now overtaken cigarette smoking as the single greatest contributing risk factor, being responsible for 8.3–8.6% of the total burden of disease and injury.

There is nothing new in the findings of this review. The results are consistent with the evidence underpinning and the recommendations of the Australian Dietary Guidelines www.eatforhealth.gov.au  and the NHMRC Clinical Practice Guidelines for Managing Overweight and Obesity https://www.nhmrc.gov.au/media/releases/2013/new-clinical-practice-guidelines-managing-overweight-and-obesity

We lose weight when our energy intake from the food and drinks we consume is less than the energy we expend from our body metabolism and physical activity. For any weight loss diet to “work” in the long term, it must be low enough in energy and, importantly, easy to adhere to over time. It also needs to provide us with enough healthy foods and nutrients to promote our health and prevent diet-related diseases. A range of dietary patterns can meet these requirements; not surprisingly different types of dietary patterns suit different people.

The findings of this review in particular are that the long-term effect of dietary intervention on bodyweight depends on the intensity of the intervention, and that when compared with dietary interventions of similar intensity, weight loss is no different while following low-fat diets than other dietary interventions, when followed for at least a year. Both these findings are well known in the nutrition field. A caution is that, as it is dietary patterns over a life long period that affect diet-related health outcomes, one year is not really a long time in that regard.

The Australian recommendations noted above do not promote low fat diets. They promote eating a wide variety of healthy foods, including healthy (unsaturated) fats. They also recommend limiting intake of energy-dense nutrient-poor discretionary (‘junk’) foods high in saturated fat, and also limiting intake of discretionary foods high added sugar, salt and alcohol, for optimum health outcomes across a range of conditions.  Around 65% of Australian adults now need to lose weight. Yet over 35% of our energy intake comes from unhealthy, discretionary choices. We just need to eat less of these, and more healthy foods- it doesn’t need to be complicated. And most Australians are aware of this. But it can be hard to follow healthy diets when unhealthy choices are the ones that are most available, accessible, affordable and advertised in our society.

I think this study has drawn together a substantial body of evidence to confirm what many have already known for quite some time. There have been comparisons made of different diets in a number of previous studies which have for the most part shown that while there may be differences in weight loss over the short term (eg greater weight loss with a low carb diet) there is no difference over the longer term and in the end a calorie is a calorie.

However, despite weight loss not differing between diets, different diets can have different effects on metabolic markers and risk factors for cardiovascular and other disease and this should be a consideration still in deciding what dietary pattern to follow.