A new weight-loss study has found that significant results can be achieved without counting a single calorie.
The study’s participants maintained an average weight loss of over 10 kilograms one year after the 12-week program finished, prompting the researchers to conclude: “This research has achieved greater weight loss at 6 and 12 months than any other trial that does not limit energy intake or mandate regular exercise.”
What did they do?
Calorie controlled diets are notoriously hard to maintain in the long-term and the diet industry makes its money “off failure, not success“.
So the 33 participants in the intervention group of this study were not asked to count calories or even increase their exercise levels. For 12 weeks, they could choose their own meals and eat as much fruit, vegetables, whole grains, legumes and natural, unrefined soy as they wanted. They received cooking classes and daily vitamin B supplements and were asked to avoid animal products, processed products and to minimise high-fat plant foods such as nuts and avocados (only 7 to 15 per cent of their daily energy intake came from fat).
A control group of 32 participants received standard medical care for the same duration without any dietary program or change.
At the end of the trial, there were no “significant” changes among the control group, while the intervention group demonstrated “dramatic” improvements, with an average of 12.1 kilograms lost at the six-month follow-up and still a steady average of 11.5 kilograms lost at the 12-month mark.
The group also reported higher self-esteem and nutritional know-how, had lower cholesterol and were using less medication.
“Previous research had highlighted reasonable weight loss [via a plant-based diet], so we knew this was possible, but very few of these studies have been randomised, which is a powerful way to reveal true effects from an intervention,” says lead author, Dr Nicholas Wright, of the study, published this week in the journal Nutrition and Diabetes.
“We were pleased with the large and sustained changes that were achieved with only two group sessions per week, while participants made their own food choices.”
He believes that, in part, the group has been able to maintain their weight-loss and health improvements because the cooking classes gave them confidence and skills.
“People need concrete skills they can learn and rehearse, especially in an enabling and comfortable environment,” says Wright, of the Royal New Zealand College of General Practice. “Social contact makes the classes more enjoyable, and people really struggle to maintain behaviour changes if they don’t enjoy them. The group setting allows people to share problems and solutions, which we felt made for effective learning. “
As for staying away from healthy fats, Wright says a little bit (no more than a handful of nuts a day, for instance) is OK but says it depends on a person’s goals.
“Once someone is at a normal weight they can reintroduce these foods without too many problems. The problem arises when people think they are good for weight loss, due to some pretty shoddy science,” he explains.
“There was one meta-analysis with nut consumption where they’ve claimed it helps with weight, but then in the small print they’ve stated it was using an energy-controlled diet.”
He also points to the work of Dr Dean Ornish and Dr. Caldwell B. Esselstyn Jr, who have both found that a low-fat, plant-based diet may be able to reverse heart disease and other chronic diseases.
“In order for weight loss, a person needs to change their energy balance: consume less total energy or exercise more. There is no way around that,” says Wright, who has followed a vegan diet for seven years.
“Taking in less energy can be ‘eating less’ – but we don’t think this is the best approach, as it’s hard to sustain being hungry. Consuming less calories doesn’t have to be actually eating less food, it can be simply eating less dense foods.
“It wasn’t restricted because we told participants to eat as much as they liked, as often as they liked. Some people were eating a very large amount of tasty food and still losing weight. Many participants reported being able to eat as much as they liked and still lose weight as one of the main reasons they could maintain the changes.”
Amanda Salis of The Boden Institute of Obesity, Nutrition, Exercise & Eating Disorders at the University of Sydney agrees.
“This is an excellent outcome, and shows the benefits of eating whole foods with minimal processing,” says Salis, who was not involved with the study. “The body is extremely adept at dropping excess weight, provided that the foods consumed are not ultra-processed foods.
“All weight loss occurs via a reduction in kilojoule intake relative to kilojoule needs. What is nice is that when whole foods are used as the basis of the diet, with a lot of vegetables and fruits, people can eat to satisfy their physical hunger and still lose weight.”
Wright adds: “This research supports the whole food plant-based diet as safe and effective. We had many significant findings, including weight loss, lowered cholesterol, less medication usage, decreased waist circumference, and increased quality of life, and this was without increased spending on food or changes to exercise levels. This dietary approach can enable people to feel empowered to improve their medical conditions, but can be used outside of this setting too.”