For many years the nutritional world has advocated that small and frequent meals spaced evenly throughout the day in conjunction with exercise is the best way to lose weight. This lifestyle has helped millions of people to drop excess pounds and is associated with many health benefits. However, there is another health-promoting way to lose weight which has been gaining momentum for quite some years now and it appears to go against everything that was previously advised. I am referring to intermittent fasting (IF).
What is IF?
IF is a pattern of eating which alternates between fasting (no food intake) and non-fasting (also known as an ‘eating window’).
Variants of IF include:
- Alternate Day Fasting – a 24 hour period of eating followed by a 24 hour period of fasting continuously in a cycle.
- Once or twice per week (5:2) – Fasting for 24 hour periods up to twice each week but never in succession of one another.
- Skipping Dinner – Not consuming dinner to create a fasting window between when you finish eating at lunch time/mid afternoon and when you eat the next morning.
- Skipping Breakfast – Not consuming breakfast to extend the fasting window from dinner the previous evening to lunch time on that day.
Your body operates around a 24-hour cycle that dictates your innate circadian clock, therefore it has been said that choosing an IF regime which accommodates this cycle is more beneficial than those which obstruct it.
Initially, claims that IF could aid weight loss were called dangerous and unhealthy. However, a study conducted by Mark Mattson kick started the idea that in fact, IF was a highly feasible and healthy way to aid weight loss and improve body composition. The study that gained the attention of Nutrition and Diet experts was originally conducted on rats. The results of the study were that IF substantially increased the lifespan of the animals along with making outstanding improvements to insulin sensitivity, body composition and neuro-regeneration capacity. IF is said to prolong the health span of the nervous system by impinging upon fundamental metabolic and cellular signalling pathways that regulate lifespan.
The research in support of IF as a weight loss lifestyle is fairly robust. It has been peer reviewed by some of the most renowned scientists in the world and works have been published in The British Journal of Nutrition and The American Journal of Clinical Nutrition in support of IF. This way of eating dates back to the times of our Paleolithic ancestors and it appears it may bring us a whole host of health and aesthetic benefits by following in their footsteps.
The evidence behind the weight loss claim is completely feasible, after all, the principle is that you reduce your overall calorie intake to put you in negative energy balance. The hormonal shifts that supposedly put you into a ‘starvation’ and ‘self preservation’ mode resulting in fat storage has been somewhat quashed by author and researcher Brad Pilon (amongst others), who presented several peer reviewed articles demonstrating this (although there are several articles in favour of this ‘preservation’ theory too). He also explained how key articles on fasting/extreme calorie restriction lasting between 24 to 72 hours had no effect on resting metabolic rate, meaning this would not promote inadvertent weight gain either!
Scientists have acknowledged that there are three major mechanisms by which fasting can benefit the body:
1. It reduces oxidative stress. Fasting reduces the accumulation of oxidative radicals in cells which prevents oxidative damage to cellular proteins, lipids and nucleic acids.
2. It increases insulin sensitivity and mitochondrial energy efficiency. This helps to slow down the ageing and disease processes associated with these mechanisms.
3. It increases capacity to resist stress. Fasting induces a cellular stress response similar to that induced by exercise in which cells up-regulate expression of genes that increase capacity to cope with stress.
There is also research linking IF to the following:
- Decreased body fat and overall weight
- Maintenance of skeletal muscle mass in periods of fasting
- Decreased blood glucose levels
- Increased lipolysis and fat oxidation
- Increased uncoupling protein three mRNA (associated with fat burning)
- Increased norepinephrine and epinephrine levels (energy)
- Increased growth hormone levels
Exercising in a fasted state is beneficial to this regimen as it complements the sympathetic nervous system along with capacity to burn fat. Ensure that you schedule your workouts accordingly as you will need to be eating 30 minutes post-exercise to maximise benefits of training.
Any principle which entails calorie restriction or fasting comes with risks. Through fasting/reducing calories you are restricting the intake of certain food groups such as protein, carbohydrates, fat, and vitamins and minerals...this is inevitable. The IF theory is that these nutrients will be replenished during the non-fasting states, however if the eating windows are not maximised, your nutritional stores will not replete exposing you to deficiencies. Ensuring your diet is nutritionally complete is not easy, three regular meals consisting of starchy carbohydrates, meat or another protein source, fruit and vegetables, and some dairy produce (or alternative calcium and vitamin source) is the best way to achieve this. However, not all of us manage this on a daily basis, which makes nutrition dense supplements a complimentary addition to this lifestyle.
To ensure overall nutritional adequacy for general health and to boost your fat loss goals, try opting for a multi-vitamin, protein and carbohydrate blend, CoQ10, fat burner and/or an omega oil blend depending on the nutrition you gain through your diet.
Fasting isn’t a lifestyle choice which suits everybody; it is just one approach of many choices which are effective to aid weight loss. However, if you want to give IF a trial run it will be a great way to practice hunger management skills which will help you remain dedicated to any weight loss diet regardless of whether you decide to stick with IF or not.
Anson MR, Guo Z, de Cabo R, Lyun T, Rios M, Hagepanos A, Ingram DK, Lane MA, Mattson MP, Intermittent Fasting Dissociates Beneficial Effects of Dietary Restriction on Glucose Metabolism and Neuronal Resistance to Injury from Calorie Intake, Proceedings of the National Academy of Sciences, 2003, 100(10):6216-20.
Martin B, Mattson MP, Maudsley S, Caloric Restriction and Intermittent Fasting: Two Potential Diets for Successful Brain Ageing, Ageing Research Reviews, 2006, 5(3):332-53.