Blood sugar wars – what’s the best diet for diabetes?
Imagine a TV program a bit like The Biggest Loser but where the aim isn’t just to see who drops the most weight but who can most improve or possibly reverse their type 2 diabetes by a change of diet over 12 weeks. This was the gist of The Saving Australia Diet airing on Channel 7’s Sunday Night last week which lined up three self-confessed overeaters- two with type 2 diabetes – the chronic disease where the body can’t regulate its blood sugar levels – and one with pre-diabetes.
The program’s question was – which of three diets would work best for reducing their weight and blood sugar?
- A high fibre eating plan with moderate amounts of low GI carbs, lean protein, vegetables and fruit – the standard approach used to managing blood sugar (glucose) levels in people with type 2 diabetes?
- The low carb, low calorie 800 Calorie Blood Sugar Diet based on vegetables, fruit, nuts, oily fish and olive oil from doctor and TV presenter Michael Mosley?
- A low carb plan similar to a Paleo diet designed by orthopaedic surgeon Dr Gary Fettke with chef Pete Evans?
The results, aired on the Sunday Night program, on September 4 were good news. All three participants had lost weight and lowered their blood glucose to within the healthy range (4.0 to -7.8mm/L). Jack Merolla, aged 50, on the 800 Calorie Diet had lost 19 kilos and dropped his blood sugar to 4.7; 65-year-old Tony Benneworth on the low carb diet had lost 22 kilos and dropped his blood sugar levels to 5; Cassandra Floyd, 36, lost 10 kilos and reduced her blood sugar to 5.5 by following a standard plan recommended by Accredited Practising Dietitian Alex Parker.
Both the low carb and 800 Calorie Diet delivered greater weight loss and lower blood sugar levels – so do they trump the standard approach that includes moderate amounts of carbs?
Not so fast, says Dr Clare Collins, Professor in Nutrition and Dietetics at the University of Newcastle.
“This is a TV show based, not on a carefully controlled long term study of hundreds of people with diabetes, but on a 12 week experiment with three people,” she points out. “The three people are quite different to each other and there’s no long-term follow-up. We need to know where their weight and blood glucose levels will be in six months to one year from now.
“Most of us can hack a change of diet in the short term – but it’s what you can live with in the long term that determines whether the weight stays off,” she says. “What’s more, in percentage terms Cassandra has lost ten per cent of her body weight – a big achievement in 12 weeks, especially given that initially women lose weight more slowly than men.”
Cassandra also had the most dramatic reduction in blood sugar – dropping from 16.3 to 5.5.
Collins, a spokesperson for the Dietitians Association of Australia, is also concerned about some of the ‘experts’ used to guide the diets in the program. Gary Fettke who helped design Tony’s low carb, high fat diet is a surgeon not a diabetes specialist. He’s also under investigation by the Australian Health Practitioner Regulation Agency and reportedly been cautioned not to advise on the nutritional management of diabetes because it’s outside his scope of practise.
Then there’s Pete Evans – a chef, not a health professional – who makes the point in the program that the problem with the nation’s diet is that ‘we’ve gone from a diet high in fat to one high in starchy carbohydrates’.
Wrong, says Collins.
“The problem is we’ve gone from eating minimally processed food to eating ultra-processed foods – figures from Australia’s National Nutrition and Physical Activity Survey show that 35 per cent of the kilojoules we consume daily come from foods like biscuits, cake, processed meats, pies, confectionary and fast food.
“The real issue isn’t why are we eating so many carbs but why are we eating so much junk? Not all carbohydrates are the same – it’s important to distinguish between highly processed carbohydrates and quality wholegrains,” she says.
“Look around the world and there’s a diverse range of healthy eating styles. The traditional Japanese Okinawan diet is high in carbs and low in fat while the traditional Cretan diet includes a lot of healthy fat – but what they both have in common is no junk food.”
Collins also queries the use of a basic blood glucose test as proof that Jack and Tony’s blood sugar was back in the normal range – a more realistic picture of the participants’ blood sugar would be a test called HBA1C that shows how well blood sugar levels have been controlled over the last two or three months – not just at one point on a single day.
Like Collins, Alex Parker the dietitian who helped Cassandra follow a high fibre low GI diet, believes the program sends a misleading message that a low carb, high fat diet or low calorie diet are the best ways to manage or even reverse diabetes.
“It’s alarming that the message has gone to so many people that a low carb high fat diet is the best way to go or that they think ‘I need to adopt an 800 calorie a day diet and my diabetes will be cured’”, says Parker. “With diabetes, it’s not a ‘one size fits all’ approach, but working with the individual to tailor a plan specifically for them. This will be sustainable in the long term.
“When someone has diabetes and is overweight, we have to look at the entire picture – they could also be at risk of other nutrition related chronic diseases including heart disease and would be advised to reduce saturated fat.”
Still, there’s a growing acknowledgment that there are different dietary approaches to managing diabetes, says Pennie Taylor, a dietitian who worked with a team of CSIRO researchers on a 2015 study over two years that found a diet high in healthy fats including nuts, avocado and olive oil but low in low GI wholegrain carbohydrates improved blood glucose control in people with diabetes better than the standard approach that includes more carbs and less fat.
“But different people respond differently to different diets,” she stresses. “We need to match each individual to the right dietary approach – that’s why it’s important to have a GP, endocrinologist and a dietitian involved.”
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