A diet low in total fat can reduce your body weight

I know, I know, it’s simply not the time of year to be worrying about this kind of thing. Feel free to finish that mince pie, close your eyes, stick your fingers in your ears and give a loud ‘Ho, Ho, Ho’ or two.

I’m sure it comes as no surprise but with the World Health Organisation wanting to update its guidelines on the recommended total fat intake in our diet, a study has been carried out to assess the relation between total fat intake and body weight. This systematic review and meta-analysis of randomised controlled trials (RCTs) and cohort studies has investigated the available evidence to look at the longer term effects of total fat intake on body fatness (obesity, waist circumference and body mass index (BMI)) in studies not intending that the participants lose weight.

Meta-analysis was carried out on 33 RCTs involving 73,589 adults.  The studies compared an intervention intended to reduce total fat intake by reducing percentage energy from fat or total fat in g/day with a usual fat intake arm.  The interventions had to continue for at least 26 weeks.  This is what they found:

  • Diets lower in total fat on average reduced body weight by 1.6kg, BMI by -0.51 and waist circumference by 0.3cm
  • Reductions in total fat were associated with small but statistically significant reductions in total cholesterol, low-density lipoprotein, and ratio of total to high-density lipoprotein cholesterol and in systolic and diastolic blood pressures
  • The analysis showed that greater reduction in total fat intake and lower baseline total fat intake were associated with greater relative loss in studies with a total fat intake at baseline of between 28% and 43% of energy but that any reduction in total fat will be reflected in some weight reduction relative to control
  • The evidence suggests that weight reduction is due to the reduced energy intake in those on low fat diets rather than a specific effect of the macronutrient composition of the diet


  • Analysis of the cohort data in adults suggested either no relation between percentage of energy from total fat at baseline and weight change over one or more years, or a positive relation (in a third of the comparisons).  This lack of association could be due to the relative insensitivity of the instruments used to measure the total fat intake, the small size of the relation being sought and the confounding effect of dieting behaviour that is common in the populations studied

The authors concluded:

Each 1% decrease in energy from total fat resulted in a 019kg reduction in body weight, compared with not altering total fat intake, in populations with 28-43% of energy from total fat, and in studies or six months to over eight years.

Although it may be difficult for populations to reduce total fat intake, attempts should be made to do so, to help control weight, where mean total fat intake is 30% or more of energy

Well there you go.  You already knew that second helping of roast potatoes on Christmas day probably wasn’t a good idea.  Not only is it going to affect your body weight but also you might be in danger of not being able to fit in the Christmas pud!

Seriously though, this is further evidence supporting the need for a healthy balanced diet.  We should all be taking control of what we eat and looking after our bodies so that we have long and healthy lives.

On that note I would like to wish you all a very merry Christmas and a healthy, happy, low fat 2013!


Hooper L ,Abdelhamid A ,Moore HJ ,Douthwaite W ,Skeaff CM ,Summerbell CD. Effect of reducing total fat intake on body weight: systematic review and meta-analysis of randomised controlled trials and cohort studies. BMJ 2012;345:e7666