One of the UK’s leading experts in appetite and energy balance, Dr. Alex Johnstone, has established that it is not clearly understood why protein-rich diets can help with appetite control. At a seminar held at Leeds University, she stated that it is difficult to measure and monitor appetite control for high-protein diets, but is it an effective way to help with weight loss. She also established that the type of protein is less important that the amount – so plant-based proteins can work as a substitute for meat-based protein.
Dr. Johnstone is a Senior Researcher at the Rowett Institute of Nutrition and Health, and her on-going research into the sustainable strategies of weight-loss dates back to 2009. She assisted with the Fuller Longer food range developed by Marks and Spencer (M&S) Plc and also leads free online health courses in food and nutrition.
The methodology consisted of comparing two different types of protein diets that were prepared daily by human nutrition staff. The diets were fed to 12 men and the effects were monitored for several weeks. Positron Emission Tomography (PET) technology was used to monitor the effects in the body.
It is understood that a high protein diet can be effective with weight loss, but Dr. Johnstone wanted to study and research why this is the case. Although her findings do not give one definitive answer, she established that the possible mechanisms for induced satiety is: (1) protein slows the rate of passage through the small intestine, creating a physical sense of fullness; (2) protein stimulates the release of gut hormones, which promote the feeling of fullness; (3) role of the liver in metabolite production from amino acids, which can be linked to the brains sensed of hunger; and (4) direct action of amino acids in the brain.
One of the main reasons people do not stick to their weight loss diet is because they feel hungry. Protein is effective at reducing hunger so you are not tempted to snack.
The vision of the research is to “develop guidelines for protein products to support healthy ageing that is cost effective, sustainable and enjoyable to consume”. Statistics indicated that shoppers are more likely to prioritise saving money on the food products they buy, than selecting a food product which they believe to be the healthier option. Only 49% of the consumers buy products based on whether they are healthy. “This depresses me,” she says. “Even though I designed one of the healthiest diets in the world, only 50% of consumers are interested in it”.
“Food is such an important part of our daily life and living. A lot of our social experiences are governed by the time of day we eat so this is all part of understanding how we can change our diet and lifestyle for the better.”
Dr. Johnstone wishes to further her research in the use of protein in weight maintenance, sarcopenia diseases in the ageing population and gut microbiota role in satiety. She is offering a free 4-week online course to tackle diet and lifestyle myths, starting in September 2017. You can register for the course at Future Learning.
PHOTO Stella Taxidi