Calories IN = Calories OUT. Is it? – Part 3

Please read Part 1 of the post first before starting here.

I quote a few examples in real life and lab studies to provide additional reading and evidence related to the observations and statements in Parts 1 and 2.

1. Growing Children

It is well known that Children start eating quite a bit during their peak growth period. Assuming their diet is balanced, Children will grow in height, will have longer/stronger bones and also put on muscle. All that eating is to support the growth (which is kicked into gear by the growth hormones) – Vertical growth (height) and not horizontal growth.

If someone says that Children overeat and that is why they grow that does not sound right. Children grow that is why they Overeat.

As soon as the growth period is over, the additional eating stops generally. This also supports our assumption.

2. Hibernating Animals

A number of animals go into Hibernation during seasons (typically winter). Prior to the start of the season, animals overeat and they also put on a lot of fat.

Once the season starts they go into hibernation during which the metabolic rate plummets, temperature drops significantly, blood pressure and heart rate become slow (all of this essentially to reduce the consumption of energy thereby saving energy).

All these indicators are consistent with our observations earlier (if you under-eat significantly – in effect you will create a mini-hibernating condition – your body thinks food is scarce and starts shutting down or reducing the function of parts of the body).

(On a slightly different note – not all animals put on fat under the skin – it depends on where they live. A polar bear puts on fat under the skin – insulation – this protects it from the cold weather as well as providing energy. But a Camel lives in hot deserts and if it puts fat under the skin it will have a problem with heat – hence the fat in a camel is in the hump. There are some animals which do so in their tails – fat-tailed animals. It is all wonderfully sorted out by Evolution!!)

3. Pregnant Women

We all know that Pregnant Women eat quite a bit and also put on both Fat and Weight. Going by conventional logic, we could say that pregnant women are getting Fat because they are Overeating.

We know better. They are Overeating because they are getting Fat. Again this is mostly due to hormones and for a very good reason. The fat is to provide nourishment to the mother and the child and also to cushion the baby’s weight (that is why the fat is mostly around the thighs and buttocks I was told).

Once the child is born the Overeating stops and the mother generally returns to her previous size (assuming a balanced meal) over a period of time.

So in essence the hormones create the condition for Overeating by pumping a lot of energy into fat for the sake of the mother and child. Not the other way around.

(A slight digression: It is very well known to the medical researchers that women are less prone to heart disease prior to their menopause (leading to a gradual decrease in Oestrogen production) – so women are cardio-protected. The researchers (well intentioned) thought this was due to hormones and have actually prescribed HRT (Hormone Replacement Therapy) to a number of women in the past and this has had disastrous results. HRT is now strongly recommended against for protection from Heart Disease for women).


In essence, the regulation of fat metabolism in humans is complex, has evolved over millions of years and tries to do the right thing at the right time in the right amounts. It is only when it gets chronically challenged does it go out of balance.

4. Zucker Rats

Perhaps the best examples to state that the Weight / Fat problem is related to Hormones and Not Overeating or Laziness (or being sedentary) are a set of wonderful experiments done with a special category of rats bred for research in Obesity and Hypertension by a researcher called George Wade et al in University of Massachussets in the 1970s. (Just to note that not all experiments that have been successful on rats have not had the same result in humans).

Part 1

Wade and team have removed Ovaries from rats and then monitored their subsequent weight and behaviour.

  • The rats began to eat voraciously and quickly became Obese (the rats have been given as much food as they wanted to eat – called “Ad Libitum” in medical terms)

Part 2

Wade then did a second experiment. He removed the Ovaries but then restricted the amount of food the rats can eat.

  • But the rats got just as fat as quickly. But these rats are now completely lazy. They moved only when necessary.

Removing the Ovaries stopped the production of Estrogen in these rats (in both experiments) and estrogen (a hormone) has a role to play in fat storage (more about this later but for now understand that less estrogen means more fat).

Part 3

Estrogen was infused into the rats.

  • The rats did not become fat or did not overeat and moved normally even if unlimited food was made available to them.

This Zucker Rat experiments should make it very clear that it is most likely the Hormones that are playing a part in Obesity and Fat Metabolism not Overeating and Laziness.


“You Overeat because you are putting on Fat not getting Fat because you are Overeating”

There are many important hormones but we will be talking about four hormones in particular in the next post – Insulin, Leptin, Ghrelin and Lipoprotein Lipase (LPL) and also about the science of Fat metabolism.

The next post will be “Why do we actually get Fat?”



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