Feasting or fasting in the festive season?

THE Christmas festivities are barely over and Chinese New Year is already rolling round. We have just recovered from the wine and dine of the Yuletide season and are trying to shed the extra kilogrammes. The gym instructors will tell you that there is a surge in the beginning of the year in gym attendance as people grapple with added body weight and the weight of their New Year resolutions! There has been a lot of interest in intermittent fasting and low carbohydrate diets. Intermittent fasting is practised in various ways. One is to fast on alternate days or to fast two to three days in a week, while an alternative way is to reduce the number of hours in a day for eating.

Hence you have regimens such as 5:2, where you fast for two days in a week, or fasting for 14 hours daily for five days in a week and gradually increasing it over months to 16 to 18 hours daily. The whole idea about intermittent fasting is to switch the body to use ketones as a fuel as opposed to glucose. The brain needs to use glucose to power itself and in fasting states, it uses ketones. The ketones comes from fat breakdown.

Caveman situation

The idea of intermittent fasting is to recreate the caveman situation where they did not cultivate crops and had to survive from hunt to hunt. The fasting state induces ketone production or ketosis and it takes only eight to 10 hours of fasting before ketones start to rise in the bloodstream. The rise is marked when the fasting period hits 24 hours. The ketones are not just a fuel; they are also powerful triggers of certain pathways that the body needs to overcome the challenge of fasting. These pathways allow the cells to mount antioxidant response, repair damaged DNA, increase number of mitochondria that are the powerhouses of the cell, remove damage structures inside the cell and reduce inflammation.

In short, the body conserves by shutting down growth and reproduction, enhancing response to stress, favouring repair mechanisms and ensuring cell survival. When the fast is broken and the patient starts to eat, the glucose levels rise, the ketones fall, the body starts to increase protein production resulting in growth and repair. Hence the intermittent fasting regimen together with exercise results in long-term adaptations that are useful. Is intermittent fasting the panacea to our growing obesity rates globally? There is a lot of research ongoing in different areas such as intermittent fasting in cancer, degenerating illnesses of the brain, asthma, autoimmune disease, diabetes, obesity and cardiac diseases.

A lot of data is in animal studies and we are still missing long-term, megasized trials. Other issues include gorging during the feeding states as you still have to restrict your calories when you break the fast; there is also irritability, hunger and “brain fog” when your brain starts using ketones as a fuel. Thankfully, these side effects resolve within a month of starting your regimen. The other popular strategy is the use of low carbohydrate diets. A healthy diet comprises of 45 to 65 per cent of carbohydrates. A moderate carbohydrate diet comprises 26 to 44 per cent, a “low” carbohydrate diet is 10 to 25 per cent and a “very low”  carbohydrate diet is 10 per cent or less. The remaining is either protein or fat. The diets that trigger ketosis are usually low or very low in carbohydrate and high in fat. High protein intake in a low carbohydrate diet can negate ketosis.

Does a low carbohydrate diet work? The data shows that such diets do work, and they can result in increased metabolism. We are not sure how this is achieved but it could be due to changes in stress and thyroid hormones. There is also remarkable initial weight loss due to loss of body water as ketones are diuretic in nature. The loss of water is also due to lower insulin levels and the depletion of the glycogen stores in your liver. The weight loss in the short term is much better than your normal low fat diet. In the longer term, that is, six months or more, the gains between low carbohydrate and low fat diet evens out. It is also very  difficult to sustain a very low carbohydrate diet. The other thing to note is that your muscle mass may also deteriorate with low carbohydrate diets and so it is important to make sure you eat enough protein and not just fat.

I am often asked if cholesterols will be affected by a low carbohydrate diet. The response of cholesterols levels may be quite varied. If the patients eats a lot of saturated fat, the LDL or bad cholesterol will rise. Hence we usually tell patients on such diets to monitor their cholesterol profiles. The triglycerides are heavily influenced by glucose and hence such diets do lower triglycerides. In diabetic patients, the triglycerides and blood glucose levels are reduced by such diets.

Not all diets are equal

Among the low carbohydrate diets, not all are equal. For example, they found the diets that were more Mediterranean and Paleolithic in nature were useful in diabetics. Those with higher protein and lower fat were also useful. Is there a down side to such low carbohydrate diets? Well, they found that it was not helpful in blood pressure patients, it may produce changes in the gut bacteria and it is not helpful with inflammation. We believe that the arteries are inflamed, therefore triggering blockages. Is there increase in longevity if we partake in such diets? The data shows that if we substitute the carbohydrates that we forego in such diets with animal fat or protein, longevity is reduced.

However, if we use plant-based fat or protein, longevity is enhanced. In the final analysis, we have found that patients do lose weight with low carbohydrate diets and intermittent fasting. We have to be aware that such diets are not fads or trick diets. One can lose weight by cutting off a leg; “trick diets” try to get you to reduce your calorie intake by making you consume too much of one item, be it pineapples or apples or whatever. Ultimately, as we leave one festive season and move into the next, be mindful of what you eat, try to eat in moderation, control your portion sizes, maintain your exercise and enjoy the goodwill and fellowship of kin, friends and colleagues.

Dr Chong Yeh Woei
Senior Physician (Internal Medicine)
MBBS (S’pore), MRCP (UK) Internal Medicine


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