Intermittent Fasting, Weight Loss & Longevity

The Reason Everybody’s Intermittent Fasting

Intermittent fasting (IF) is the popular term for a dietary programme that includes relatively short periods of time when only water is consumed. Alternatively, an ‘absolute fast’ or ‘dry fast’ is defined as abstinence from all food and liquid for a set period. One of the more popular IF options is to fast for 12-hours each day (Time Restricted Fasting), whilst another format encourages fasting for one or two days each week (Alternate Day Modified Fasting). Intermittent fasting has become a subject of interest and popularity after the launch of “The 5:2 Diet” book (2012) and several documentaries, such as the BBC’s “Eat, Fast and Live Longer” (2014). IF is now a widely employed method to help us lose fat and improve our health.

In Embody’s personal training facilities, many of our clients report having tried some variation of this diet. Most health-conscious individuals actively seek to change or improve their dietary habits often as better evidence is discovered. There are some common questions around this particular diet we are often asked;

“Will intermittent fasting help me lose weight?”
Or, “Is intermittent fasting healthy?”

The short answer is, yes. There is now plenty of evidence to suggest that IF can help us with weight loss and longevity. However, this article will discuss whether or not intermittent fasting is better than other dietary plans/structures to achieve the same results. After all, many diets and nutrition programmes can help you lose weight and feel better. What interests us is; which offers the greatest benefit to you as an individual?

How does Intermittent Fasting cause weight loss?

There are two primary mechanisms at work in the role of the effectiveness of IF with regards to weight loss.

1. By limiting the period of time we eat during a day (for example), we typically consume less food overall and therefore reduce our total intake of energy.
2. By limiting the period of time we eat, and therefore removing the constant availability of energy in our blood, our body becomes more insulin sensitive.

Of these two mechanisms, the first (limiting our intake of food) has proven the most consistent weight loss factor across all research. Of all the different physiological mechanisms leading to weight loss, one of the most fundamental is the theory of energy balance. If all other variables in your life are controlled (your exercise habits, the type of foods you choose, your sleep patterns etc.) consuming significantly less energy will result in weight loss.

Note: It’s important to understand that, whilst significant restriction will result in weight loss, this does not limit the weight that you lost to body fat alone. If only it were that simple! To learn more on this subject, click here.

For most of us, accountability and structure are big factors in dietary adherence. For example, if you typically become drowsy and hungry at your desk in the early afternoon, stating ‘a rule’ that you are not allowed to eat during this period has proven an effective strategy. Similarly, if you do not want to track your dietary intake in order to guarantee a consistent amount of energy is consumed, creating a time of day when you must stop eating helps mitigate over-consumption.

Fasting to improve insulin sensitivity has been successfully used in various populations and found particularly significant in the role of reversing type 2 diabetes. Eating multiple times every-single day is a recent luxury. For many of us, it may be that there are few occasions each day when we are not eating or drinking something. Whether we are catching up with friends, attending meetings or walking from station-to-office, we often eat or drink something. Many of us always have ‘new energy’ available in our blood, and therefore no need to metabolise body fat.

Research has shown this constant state of ‘storing energy’ (in the form of lipids and sugars) impairs our cells sensitivity to insulin. This affects our health and our ability to lose weight. Fasting promotes insulin sensitivity and improves our body’s ability to appropriately manage blood sugar, supporting weight loss.

Is intermittent fasting better than other diets?

If we took two ‘average people’ (identical twins perhaps) and gave each of them the same amount of the exact same foods to eat but controlled all other variables, both would lose the same amount of weight. For most, the time period across which food is consumed doesn’t seem to matter all that much. The vast majority of human research is remarkably consistent in finding that controlling energy balance is the more relevant mechanism for weight loss. Clinical trials also agree that weight loss is the more significant factor in improving insulin sensitivity.

IF absolutely helps control total intake and improves insulin sensitivity in those that take an intelligent approach. However, reviews in the Journal of Clinical Nutrition and International Journal of Obesity show the weight loss and insulin sensitising result of IF as being only similar (and no better) to that found with fundamental energy restriction. Therefore, it is very difficult to conclude that IF is better than other diets with the information we have today.

How to use this information?

Whilst it can’t be concluded that intermittent fasting is a better diet, or that it will help you lose weight and improve your health any faster (or to any greater extent) than another diet, the effects can be fantastic if used well. Deciding to try a variation of fasting (be it ‘time restricted’ or ‘alternate day fasting’) then becomes subject of personal preference and practicality.

For example, if you want to lose body fat and experience the associated health benefits but do not wish to track your intake, IF might be an effective solution. If over-consumption at a particular time of day, or day of the week, are causing your weight loss and health efforts to fall short, setting a rule to limit intake at these times demonstrates a logical benefit.

Effective nutrition is as much about consistency and practicality as it is the details. What is perhaps more important than finding the most healthful diet, is finding or designing a diet that allows you the success that comes with consistency and convenience. In our experience, these are the areas where are our nutrition team do their best work and the factors that have the greatest impact on your results in the long-term.

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If you’re hungry for more, try this article; “London’s Healthiest Breakfast“.