The keto diet is a low-carb, high-fat diet that was initially prescribed for epilepsy in the 1920s. These days, the keto diet has become a star in the dieting world. Why? Because it works. Following the keto diet results in rapid weight loss in a short period of time.

Like Atkin’s diet which was popular in the 1970s, keto forces the body to use ketones (a by-product of the breakdown of fat) as the main source of fuel instead of glucose. This is termed ketosis and it mimics a fasting state, which is a normal reaction when food is temporarily limited as the body has to rely on its own fat stores.

On keto, carbohydrates are severely restricted to around 5-10% of total energy per day (equivalent to two bananas). This is significantly lower than recommended by the Australian Nutrient Reference Values, which signals that 45-65% of daily energy should come from carbohydrates to reduce chronic disease risk and obesity. The keto diet is also typically low in fibre, which in turn affects gut health – evidence suggests that poor gut health could be linked to obesity.

One of the main problems with the keto diet is that it cuts out significant food groups, which can cause constipation, dehydration, micronutrient deficiencies, and bad breath. It also makes it hard to adhere to a normal lifestyle and makes socialising difficult (no pizza nights with friends and having only one or two options to choose from at a restaurant).

New evidence from Yale University indicates that in animals, the keto diet may have positive outcomes in the short term, but can have negative effects after a week. In humans, over a one to five-year period, there is strong evidence that indicates there is no difference in weight loss by doing keto compared to reducing calories moderately.

“A keto diet isn’t recommended for the general population, as the long-term efficacy and safety of the diet are unknown, having only been studied in the short-term.” Dietitians Association of Australia

Diet culture

There’s no one-size-fits-all when it comes to dieting, and some of the more popular ones, focus on quick fixes rather than the bigger picture. Dieting does work in the short term, however, the long term evidence paints a different picture. Studies into the effects of dieting show that one to two-thirds of weight lost via dieting is regained within one year, and almost always comes back within five years. On top of that, at least one in three dieters regain more weight than they lost.

In a recent review, researchers from the University of Minnesota found that the average amount of weight lost on diets was less than one kilogram after two years. This is where the trouble begins – people don’t blame a diet for not working, they place the blame on themselves.

There’s a lot of shame, body hate and low self-esteem in the dieting world. Research indicates that dieting is the number one risk factor for developing an eating disorder and that dieters are six times more likely to develop an eating disorder.

So, why don’t diets work? The restrictions, counting calories, macronutrients (and more), can be psychologically damaging – this creates a stress response, which facilitates weight gain rather than weight loss. How’s that for irony? Additionally, when we rapidly reduce our energy (food) intake, our bodies go into a famine reaction. This means that the metabolism slows down, appetite increases, and physical activity decreases. This is our body's survival mode and prevents further weight loss, leading to weight gain.

The key takeaways

The National Weight Control Registry is a US database of 10,000 people who have lost weight and successfully kept it off for at least a year. It serves as a study to find out why some people are more successful at losing weight than others. Common characteristics of people who have successfully maintained weight loss include:

• Eating breakfast every day
• Watching fewer than 10 hours of TV/streamed videos per week
• Exercising for an hour a day (on average)

So, what’s the verdict? Keto can work for short-term weight loss, but it may be a waste of time if someone is looking to lose weight in the long run. For the latter, reducing energy intake over time, paired with exercise, is what will get results – a maximum of two to four kilos of weight loss per month is a healthy amount.

If you’re on a weight loss journey for the long run, it’s important to take a break from energy restriction to reduce the famine reaction we mentioned above. This is called interval weight loss – you lose a bit, maintain, lose a bit more, and so on until you reach your goal.

References

Dansinger, ML, Gleason, JA, Griffith, JL, Selker, HP & Schaefer, EJ 2005, ‘Comparison of the Atkins, Ornish, Weight Watchers, and Zone Diets for Weight Loss and Heart Disease Risk Reduction’, JAMA, vol. 293, American Medical Association, no. 1.

Dulloo, AG & Montani, J-P 2015, ‘Pathways from dieting to weight regain, to obesity and to the metabolic syndrome: an overview’, Obesity Reviews, vol. 16.

IBIS , 2019 . Weight Loss Services – Australia Market Research Report. Weight Loss Services industry trends (2014-2019).

Ketogenic diet, Fad or Future. Professional Development Seminar, Matt O’Neill APD.

Mann, Tracey (2018) ‘Why do dieters regain weight?’ Psychological Science Agenda.

National Eating Disorder Collaboration (2020) Research Portal.

Swinbourne, J 2019, ‘Boden Obesity Management workshop’.

Tomiyama AJ, Ahlstrom B, Mann T. ‘Long-term effects of dieting: Is weight loss related to health?’ Social and Personality Psychology Compass 2013; 7(12): 861-877.

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