Dietitian Susie Burrell spoke with Professor Grant Brinkworth, a senior research scientist from CSIRO, about the negative side effects of the Keto diet on weight loss. And apparently, the popular diet could lead to long term weight gain – not loss.
There are few diets that received the attention of the keto diet in recent years. The high fat, low carbohydrate approach to weight loss and eating which is associated with relatively quick weight loss and reports of both physical and cognitive benefits from this relatively strict diet.
While keto devotees swear that they have never looked or felt better, the rigidity of keto can mean that it is not for everyone, and while some people may report rather drastic results initially, in order for keto to be effective long term, to support short and long term weight loss, certain criteria will need to be met.
There is also some new research to show that keto may have an adverse effect on our metabolism long term, ultimately making it easier to gain weight over time. So if keto is your thing, here are the potential issue you need to be aware of, and the easy way to avoid this side effect long term.
Like what you see? Sign up to our bodyandsoul.com.au newsletter for more stories like this.
What is the keto diet?
The keto diet works by shifting the body from burning glucose from carbohydrates as its primary source of fuel to instead burn ketones that come from fat stores being mobilised and used as an alternative fuel source. When the requirements for keto are achieved, or carbs are kept low enough, keto can be an extremely effective way to shift kilos relatively quickly.
While this may sound great, the reality is that achieving ketosis is not that easy, with the diet need to restrict all types of carbs including fruits, veggies, cereals, grains and legumes which leaves a diet full of a lot of nuts, seeds, avocado, oily fish and plain salad. This can be difficult for many to maintain long term.
What are the side effect of the keto diet?
For those who do like to eat this way, and who have successfully lost a number of kilos on keto, one of the potential side effects is that rapid weight loss not only translates into fat loss, but also muscle mass loss. As muscle mass is a body tissue that actively burns calories, reductions in muscle mass over time will reduce metabolic rate. This means that ultimately you will need fewer and fewer calories over time.
This may also explain why individuals who experience initial success on low carb diets not only regain weight more quickly, but who also find it difficult to repeat the initial success they achieved when they try eating low carb again.
Keeping the weight off could prove difficult
Clinical research conducted by metabolism researcher Dr. Kevin Hall currently awaiting publication, compared the effects of a high carb diet and keto on weight loss, changes in body composition and glucose control in 20 overweight adults. Here study participants could eat as much or as little as they liked at each of three meals and two snacks in their diet over a two-week period before they swapped and completed the opposite diet for another two weeks.
While the study was short term only, researchers found that while the high carb diet resulted in slower weight loss, both diets yielded similar weight loss results but the keto diet resulted in a far greater loss of muscle mass than the high carb diet. Long term this effect has significant consequences for metabolic rate and may explain why those who get good results on the keto diet initially struggle to keep the weight off long term.
What do the experts say?
Professor Grant Brinkworth, a senior research scientist from CSIRO says that although this is a strong scientific study we do need to be careful how we interpret these results as the study was only undertaken with 20 participants, and the measures used to determine the type of weight that was lost were not perfect:
“This study used DEXA scanning to infer fat-free mass loss which would also include water losses which are known to be impacted in the early phases of low carb, ketogenic diets. It really is too short a study period to infer long term metabolic consequences of this. In the low carb studies, I have been involved in for building and maintaining muscle mass combining a higher-protein diet with regular resistance exercise training is an effective approach for people wishing to improve their body composition by reducing their fat mass levels and increasing their lean body mass levels.”
Resistance training might be the answer
It is well documented in the literature that quick weight loss is associated with a strong risk of weight regain. One of the key ways to avoid this will be to ensure any restrictive diet, whether it is low carb or low calorie includes some form of resistance training to help prevent muscle mass loss. In addition, while you may use these diets to lose weight initially, long term a more moderate approach of a reduced carb but higher protein diet may be a better option to help preserve muscle mass and metabolic rate.
Professor Brinkworth agrees, “A key take-home message for dieters who choose to a follow low carbohydrate, ketogenic diet to help minimise muscle mass loss you need to ensure that there is more protein in your meal plan and that advice from an Accredited Practising Dietitian can help to determine the optimal dietary protein take for you.”
“Research we have conducted at CSIRO, consistently shows that energy-reduced diets that are higher in dietary protein help to minimise the loss of lean mass and maximise fat mass loss when we lose weight, particularly when combined with resistance exercise training.”