Why “when” you eat is more important than “what” you eat

Many of us have heard of intermittent fasting – it’s of course, the latest arrival on the stage of a looooooong list of eating habits and diets touted to initiate weight loss.

The magical qualities that intermittent fasting bestows upon the practitioner seems supernatural, so much so that it’s become cool now to catchphrase 16*8 or 14*10 as a healthier way to live your life.

But is it all true?

As someone who has had three generations of diabetics in her family tree, I was also curious about the supposed heightened insulin sensitivity that intermittent fasting bestows upon the practitioner consequently reducing the risk of diabetes.

So what is intermittent fasting?

At a glance, it’s fairly straight forward. You eat for 12, 10 or 8 hours a day as per your normal eating patterns while you fast for the reminder. During this “fasting” window, only water does not break your “fasted” state, consumption of anything else reverts your body to your “feeding” state and initiates digestion, insulin secretion, glycogen storage and so on. But the emphasis is on the number of hours within which you eat, not so much on reducing the amount of calories that you currently consume. (Of course, its advisable to avoid junk food, eat a balanced diet, etc…)

What is so important about this fasting if you are not reducing any calories anyway?

The answer lies is how your body has evolved to function after a millennia. When your body digests food, besides the immediate glucose demands, the rest of the food fuel is first converted to glycogen for future use and stored in the liver. But the liver has limited capacity! The reminder of this food fuel is stored as fat in your body adipose tissues. The higher the amount of body fat you have, the higher the possibility for developing insulin resistance as a precursor to diabetes. (Your fat cells don’t like insulin!)

The answer to reducing the health risks due to excessive weight is to…. ahem… reduce weight. So how does intermittent fasting do this without reducing your calorie intake?

The answer lies in creating favourable conditions for your body to do this work. There are certain hormones and enzymes that are secreted in your body only when you are in a fasted state for a minimum of 12 hours. Human growth hormone is a prime example – this hormone supposedly combats ageing and helps in production of collagen which helps in a younger looking skin and better hair growth. Again, if you are in a fasted state of 12 hours or more, your body depletes the glycogen in your liver and starts breaking down fat in your adipose tissues resulting in weight loss over the medium term. Intermittent fasting also helps those with the fatty liver syndrome in reducing the risk of liver cirrhosis.

Which brings me back to the title of this post – why is when we eat so important if all you have to do is to fast for 12, 14 or 16 hours? Does that mean you can fast from 8am to 8pm while having jumbo meals in the evening?

Of course not!

Recent research has also shown that when or at what times of the day you eat is as important as the quality and quantity of your diet.


This brings us to the concept of time restricted eating. In theory, the underlying principles of both these methods are the same. You have a fasting window of 12, 14 or 16 hours depending on your preferences and subsequently, you have a feeding window of 12, 10 or 8 hours when you eat. The divergences appear when you analyze the timing of such fasting or feeding window. Intermittent fasting emphasizes on the number of hours you fast but time restricted eating is all about your feeding window being aligned to the circadian rhythms of your body.

Our body and in fact each cell in our body has a circadian clock at DNA level. Light is a predominant factor in deciding when you wake up, what time you feel sleepy, when certain enzymes are secreted in your body, which organs function efficiently at what times and so on. Food is a secondary factor in resetting this circadian clock.

Every time your living patterns fall outside of this circadian rhythm, your normal state of “healthfulness” is disrupted. Knowing when to eat and when to sleep is perhaps more important in tackling obesity than knowing “what” to eat.

When is a good time to eat then? How does exercises/physical activity play a role in the overall health of your body?

Stay tuned for answers to these questions in my next post…….


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