Eating little and often is frequently cited as the holy grail to health, weight loss and blood sugar balance. Nutritional therapists abide by this golden rule and it is no doubt an effective way to keep energy levels stable and hold food cravings at bay. In recent years, however, a new kid has arrived on the block which advocates the exact opposite; the newcomer is called ‘fasting’ or, more precisely, intermittent fasting (IF).
IF is based on the principle of missing certain meals and severely restricting food intake at certain times – even skipping breakfast is allowed! A solid evidence base is emerging that supports the notion of IF and its health benefits are hard to dispute; improved energy levels, a stable blood sugar curve, weight loss and crucially an increased rate of fat metabolism. Should we be throwing our long held beliefs out the window, or should we hold on to tried and tested methods? These are the questions I will attempt to answer.
The benefits of having 3-meals-and-2-snacks are well studied and a core principal of clinical practice; by supplying the body with a steady stream of nutrients and complex macronutrients we are able to prevent blood glucose levels from rising too high or falling dangerously low. In response, less insulin is needed to control sugar concentrations which can prevent cravings, over eating, fluctuating mood and erratic energy levels. This approach is especially beneficial for diabetics who need to keep a very close eye on carbohydrate consumption and it has proven effective in sensitising cells to insulin, improving insulin resistance. The concept of ‘little and often’ is based on the assumption that our body, and more so our brain, needs a constant supply of glucose. But what if this isn’t the case? What if our body actually prefers to use fat as fuel and can function very well (or even better) in a state of low glucose but with a ready supply of fatty acids?
Now we are venturing into the somewhat unchartered territory of intermittent fasting. The whole idea is based on the evolutionary principle that food in cavemen times would have been scarce. It is not difficult to imagine that three square meals and a couple of balanced snacks were hard to come by in a dangerous and unstable environment. Nevertheless, our species has flourished under conditions of irregular food intake and we should be perfectly adapted to gorging when food is available and fasting when times are lean. Our body might have even evolved to work most efficiently under such circumstances, which goes against all modern principles of blood sugar control. Not too long ago it was believed that the world was flat and anybody claiming otherwise was deemed insane. Maybe it is time to change our beliefs and investigate those heretics who advocate IF more closely.
Science paints a very clear picture; severely restricting food intake to 500 kcal over a 16 to 24 hour period has shown to promote a state called ketosis. This new way of being favours the metabolism of fatty acids as fuel for your energy producing cells but also for your brain cells. Fat stores are metabolised more efficiently while keeping blood sugar levels nice and low. Without constant, and often excess, glucose in the blood stream, insulin becomes much less of a factor and keeping this hormone at bay has shown to be beneficial for almost any chronic disease; from cancer to heart disease and diabetes, high insulin levels are a major culprit that drives the disease and inflammatory process. In the world of IF, insulin is simply not an important player anymore! Another benefit of this new approach to diet is a reduced production of free radicals; without glucose constantly knocking on cell walls, damage to proteins, fats and cell membranes themselves is greatly reduced, slowing the progress of aging and disease. Cells that are starved of glucose initiate a stress response, much like we see during exercise. Certain genes that make us more resistant to stress and disease are upregulated and therefore offer unrivalled protection against conditions such as cardiovascular disease.
IF is all about a structured approach to random food intake and several ‘diets’ have sprung up, such as the 5:2 programme. This variation advocates normal food intake for five days of the week and a severe calorie restriction for the remaining two (600 kcal for men and 500 kcal for women). Such a radical fluctuation in food intake is not for everyone and I personally prefer to practice a little bit of fasting every day. This means restricting food intake to six hours of the day, maybe even just four: instead of getting up and having breakfast, delay your first meal of the day until 11 o’clock. Follow up with a substantial lunch two to three hours later and a small snack around 4 pm. For the rest of the day (and night) the only thing to pass your lips will be water or herbal tea. Skipping your dinner (or just having it a lot earlier in the day) has been shown to be especially effective in reducing insulin levels but also increasing beta oxidation of fatty acids – also called fat burning.
In my opinion and in the opinion of emerging research, IF is the most natural and cell protective way of eating. Its benefits far outweigh the practice of grazing and it favours our natural and inbuilt mechanism of utilising fatty acids for energy and repair. However, leaping straight into fasting is not advisable, especially if you are battling with erratic blood sugar levels or insulin resistance. Introducing regular, and most importantly balanced, meals is always the first step that has to be taken; only when energy is stable and cravings are at bay should IF be introduced in order to avoid plunging blood sugar levels and the ultimate gorging on high-sugar and high-fat foods. Fasting should be introduced slowly, narrowing your window of food intake from ten to six (or even four) hours gradually over several weeks. Bear in mind that it will take your body some time to switch from glucose dependence to a state of fatty acid oxidation – this does not happen overnight and can take several months to achieve. Once you have retrained your body to function in its original state (which is a fasted one), you will enjoy the benefits for a lifetime to come!