YMCA Healthy Living Magazine, powered by n4 food and health Winter 2019 | Page 8

CATHERINE SAXELBY, APD Catherine is an Accredited Practising Dietitian and Nutritionist who has researched and written on almost all aspects of healthy eating. Her skill lies in translating scientific research into real nutrition terms. Catherine is the author of 12 books including her Complete Food and Nutrition Companion (Hardie Grant). She also runs the Foodwatch website, offering nutrition information for consumers (www. foodwatch.com.au) LOW CARB, HIGH FAT DIETS: ARE THEY SAFE AND DO THEY ACTUALLY WORK? Exploring the safety and effectiveness of the ketogenic diet craze, with Catherine Saxelby. LOW-FAT VS LOW- CARB In 2018, researchers at Stanford University published the findings of their DIETFITS Randomised Clinical Trial (RCT) involving 609 overweight adults. They were interested in whether gene patterns or insulin secretion seemed to affect weight loss, or predict who did better on the two diets. Participants were split into two groups, with half following a healthy low-fat diet and the other half, a healthy low-carb diet. At 12 months, they were weighed and any changes noted. The results n recent years low carb, high fat (or ‘ketogenic’) diets have gained a lot of air time and popularity. Low carb devotees will tell you it’s the best way to eat for weight loss, and that it’s more of a healthy lifestyle than a diet. We asked one of Australia’s favourite nutritionists – Catherine Saxelby – for her thoughts on the safety and effectiveness of low carb diets. I First things first, what are carbohydrates, and what does a low carb diet look like? Carbohydrates are one of the main sources of fuel in our diet. They break down to glucose in our blood, which may then be either used for energy, or stored by the body (sometimes as fat). Carbohydrate foods include fruit, starchy vegetables, cereals/grains (e.g. bread, breakfast cereal, pasta) and legumes. Refined sugars used to sweeten foods, such as sucrose (table sugar) and honey are also carbohydrates. 8 Even milk contains a natural carbohydrate called lactose. Low carb diets either omit or drastically reduce the food groups above. And when the body is starved of carbohydrate, it must use alternate sources of fuel. Essentially, ketosis (the goal of low carb diets) means our bodies run out of glucose, and are forced to produce an alternate source of energy – ketones – for fuel. This usually involves the breakdown of body fat and muscle, in order to keep us alive. Sounds drastic, doesn’t it? It also sounds like a good way to shed weight quickly. But does it actually live up to all the hype, and does it cause sustained weight loss? Let’s weigh up the impact of a low-carb diet versus a low-fat diet on overweight adults (see red box on the right). What does the science mean? What you need, and what I’ve always advocated, is an all-round healthy diet. YMCA HEALTHY LIVING MAGAZINE WINTER 2019 After 12 months, the group on the low-fat diet had lost on average 5.3kg and the low-carb group, 6kg. Not the huge difference often spruiked by advocates for one or the other regime, and not a clinically significant difference in scientific terms! Of note: both groups in this study were asked to kick off with a very low level of either carbohydrate (less than 50g per day) or fat (less than 20g per day). And neither group was able to maintain this very low level for the required two months! Both the very low-fat and the very low-carb diets were unsustainable – something dietitians have been saying for ages! This study did not show any significant relationship between genetic makeup or insulin levels, and ability to lose weight. In other words, these factors didn’t give us any additional insight into which people would succeed on either diet.