Protein Shake and measuring tape

Rapid Weight Loss vs. Slow Continuous Weight Loss

Weight loss protocols can only be considered successful if they deliver consistent results over the long term-a goal which is often elusive, so much so that the term ‘yo-yo’ is used to describe the perennial weight loss/weight regain battle common in obesity. A successful weight loss diet produces a loss of 10% of more of initial body weight maintained for at least one year.

Slow continuous weight loss has been shown to result in continued weight loss and long-term maintenance; however, this only occurs if the subject is able to maintain the changes to diet and physical activity.

On the other hand, rapid weight loss (RWL) diets show greater initial weight loss as well as larger total weight loss long-term. Initial RWL is related to more positive quality of life changes which can serve as motivators and reinforces of health habits and behaviours.

What is a Rapid Weight Loss diet?

Rapid Weight Loss is usually achieved using a Very Low Calorie or Energy Diet (VLCD or VLED). These diets are usually ketogenic as they contain very low levels (20-50g) of carbohydrates. This leads to the production of ketones as the body switches to primarily burning fat as its fuel source rather than glycogen. This metabolic condition is called ‘nutritional’ ketosis.

Ketones are a by-product of this process and assist in the weight loss process by its effect on appetite control hormones leading to appetite suppression.

Ketogenic diets also work to reduce fat-storage and enhance fat-breakdown, improve the body’s ability to burn fat as a fuel and increases the metabolic cost on the body as it has to produce new glucose and the increase amount of energy used to breakdown proteins.

Adequate protein intake is important when following these diets to prevent loss of fat-free or muscle mass. Greater percentage of muscle mass loss during weight loss have been associated with weight regain

A recent study that looked at subjects following VLED ketogenic and non-ketogenic protocols for six months followed by a Mediterranean diet for six months saw no weight regained in the six-month period. The evidence is now showing that VLEDs result in greater initial weight loss and along with an active weight-maintenance program including nutrition, behavioural therapy and exercise results in greater total weight loss and improves long-term weight maintenance.


  • *Paoli, A., Bianco, A., et al (2013). Long term successful weight loss with a combination biphasic ketogenic Mediterranean diet and Mediterranean diet protocol. Nutrients 5, 5205-521
  • *Vink RG, Roumans NJ, Arkenbosch LA, Mariman EC, van Baak MA. The effect of rate of weight loss on long-term weight regain in adults with overweight and obesity. Obesity (Silver Spring). 2016 Feb;24(2):321-7. doi: 10.1002/oby.21346.
  • *Paoli, A., Ketogenic Diet for Obesity: Friend or Foe?, Int J Environ Res Public Health, 2014 Feb; 11 (2): 2092-2107.
  • Bueno N.B., de Melo I.S., de Oliveira S.L., da Rocha Ataide T. Very-low-carbohydrate ketogenic diet v. Low-fat diet for long-term weight loss: A meta-analysis of randomised controlled trials. Br. J. Nutr.2013;110:1178–1187. doi: 10.1017/S0007114513000548.