GI Symbol News with Dr Alan Barclay

[ALAN]

Dr Alan Barclay

Maintain weight loss with a low GI Diet and a little more protein

The Diogenes Study, which was set up to investigate whether people who have undergone recent major weight loss could maintain that lower weight, has been published in the New England Journal of Medicine . The researchers led by Professor Arne Astrup at the University of Copenhagen conclude that: ‘A modest increase in protein content and a modest reduction in the glycemic index led to an improvement in study completion and maintenance of weight loss.’

In this collaborative project from 8 countries in the European Union (Denmark, the Netherlands, the UK, Greece (Crete), Germany, Spain, Bulgaria and the Czech Republic, 938 adults took part in an 8-week, low-calorie weight-loss diet to achieve a weight loss of 8% of their original starting weight (for most participants this was about 11 kg or 24 pounds.) Those successful in meeting this target were then given the opportunity to take part in the 6-month ‘preventing weight gain’ stage of the study.

The researchers then randomly assigned 773 adults to one of five diets for a 26-week intervention period. These were not calorie controlled diets – those taking part could eat as much food as they liked from their assigned diet group. Participants were on average 41 years old and were all parents. Their families, although not part of the trial, were assigned to the same diets. All five diets were designed to have a moderate fat content (25–30% of total energy). The diets were:

Group 1: Low protein (13% energy consumed), low GI
Group 2: Low protein, high GI
Group 3: High protein (25% energy consumed), low GI
Group 4: High protein, high GI
Group 5: Control diet which followed current dietary guidelines without special instructions regarding GI levels

A total of 548 adults (71%) completed the 26-week diet trial period. Fewer people in the high-protein, low GI groups dropped out than in the low-protein, high-GI-group (26.4% and 25.6% respectively, compared to 37.4%). The researchers found that both low GI diets and high-protein diets were equally effective in preventing weight regain. But they also found that participants in Group 3 which combined both low GI and high-protein strategies continued to lose weight over the 26 weeks of the study – see graph.

Change in body weight in Diogenes study

Note that although described as ‘high protein’, the 25% protein in the Diogenes study is less than Atkins and Zone diets (30%) and the CSIRO Total Wellbeing diet (33%). The GI of the high GI diets achieved by the participants was around 60 (pretty typical for developed nations) and the ‘low GI’ diets around 55 (not that low, but a step in the right direction).

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