A thing of the past or the way of the future?

There’s not one diet that has been widely hailed as the golden diet to success. For years, many diets have been proposed, some with accredited scientific backing and some with nothing but an idea. To use the phase, ‘there’s more than one way to skin a cat,’ this is definitely true for nutrition. A diet has to be considered useful if it results in the desired outcome, although caution should always be used, because a diet may work for one person, but that doesn’t necessarily mean that it will work for everyone. Platform Nutrition wants to dig deeper into the growing popularity of fasting for weight loss, the pros, the con’s and the possibilities.

For decades, ingrained in the western culture, main meals are eaten three times per day - breakfast, lunch and dinner, but is this purely cultural or is there physiological nutritional reasoning behind it? Perhaps a question that remains unanswered, however what is known, is that overconsumption leads to metabolic imbalances and weight gain - A growing problem in the world today. 

Dietary Evolution

Of course things change, the world evolves, we evolve albeit very slowly, but it's interesting that as mammals we have been built to withstand periods of food scarcity. The liver and adipose tissue act as a larder in times of starvation by storing energy for later use. There is however a societal conflict - in this day and age societies and communities no longer need a self storage, as food is just around the corner – the day of the hunter gather is a thing of the past.  

In spite of this, a growing dietary trend particularly in overweight individuals is fasting. Fasting has been a religious practice for centuries but dietary fasting for weight loss is a more recent phenomenon. This article is going to concentrate on the three most observed and researched dietary fasting practices:

  • ADF - Alternate Day Fasting (70% energy restriction every other day).
  • IF - Intermittent Fasting (16-48h) (500-700 kcal a day for 2 consecutive days per week).
  • TRF - Time Restricted Feeding (8h or less) (restricted for intake to a particular time).     

Fasting - which one is best and why? 

Let me explain it like this. If you have a small fridge (fat storage) you'll need to go to the shops more often and less likely to cope with long periods of minimal food (fasting). In context this is what is likely to be observed within non-obese individuals. Whereas if you have a medium to large fridge (overweight to obese) your shopping requirement and the tolerance to fasting will be greater compared to the non-obese. As such longer fasts, such as IF and ADF should be for obese individuals and TRF would possibly work better for non-obese individuals.

The benefits of fasting can stretch to a wider audience than just the morbidly obese, but the fasting period needs to be tailored to the individual. Fasting can be difficult, especially in the early days of a diet but why do it at all?

Benefits of fasting

Less in more out, the mathematics of weight-loss seems very simply, however the practical application is likely to be more difficult, but clearly fasting is an obvious suggestion to help instigate weight loss. Putting that aside for a minute, fasting also appears to offer a multitude of health benefits:

  • Enhanced cognitive function,
  • Increased insulin sensitivity,
  • Ketone generation & activation, lipid (fat) mobilisation,
  • Decreased resting heart rate and blood pressure,
  • Reduction in body and visceral fat

From the scientific data it is clear to see that despite an individual’s first thought of fasting, it actually has a high percentage of completion compliance compared to more conventional caloric restricted diets (CRD). It also has a high percentage of helping people change/improve their eating habits in the non-fasting days. On face value, it all looks promising but it must be noted that there are very few randomised controlled trails (RCTs) that have assessed fasting diets versus CRDs. In addition, most of the studies conducted in fasting have been in the morbidly obese population and therefore limits any generalisation. The last and possibly most important point before locking up your cupboards is the fact that to date no long term studies have been completed, so there’s is little to no data to prove or disprove any long term effects of fasting.

One thing’s for sure, this is definitely an interesting area of nutritional science and one that may have some significant benefits to reducing the every growing obese population of the world.

Always consult professional advice before changing your dietary habits.

References

Matarese, L. E., & Pories, W. J. (2014). Adult Weight Loss Diets Metabolic Effects and Outcomes. Nutrition in Clinical Practice, 29(6), 759-767.

Antoni, R., Johnston, K. L., Collins, A. L., & Robertson, M. D. (2017). Effects of intermittent fasting on glucose and lipid metabolism. Proceedings of the Nutrition Society, 1-8.

Mattson, M. P., Longo, V. D., & Harvie, M. (2016). Impact of intermittent fasting on health and disease processes. Ageing Research Reviews.