Calories IN = Calories OUT. Is it? – Part 2

If this is your first visit to the Blog please go to Introduction.

Go to Part 1 of this post if you have not already read it.

1. Energy Consumed (or Intake of Food / Drink)

One of the ways proposed to lose weight is to reduce the total calories consumed (let us assume the composition of Diet does not change) – so essentially eat less food/drink.

If you eat the typical diet (High Carbohydrates, Low Fat, Low to Moderate Protein) but cut down the calories quite a bit, you are unlikely to lose significant weight in the long run. This has been proven in a number of studies. (I myself have given up breakfast for a good 18 months in order to cut down my calories and it made practically no difference to my weight).

There are many studies to prove this. Some of the studies used calorie intake as low as 600 or 1000 Cals. There is an initial weight loss which is regained in an year or two. Also this level of intake was not sustainable for a long term and once the medical trial is over study subjects (or participants) ate much more than they used to eat prior to the study and regained the weight. They sort made up for the lack of food in during the trial.

Body adjusts (lowers) the base metabolic rate and also there is less energy available for  exercise / work if the intake is less than what is needed. In some studies, the body also cannibalised the muscle and tissue if the calorie intake is drastically reduced. So EM (Energy for Metabolism) and EE (Energy available for Exercise) will get reduced if EC (Energy Consumed) is too low. This is the dependency that kicks in and so EE and EC are not as independent as we think and this not considered by people quoting Calories IN => Calories OUT or the laws of thermodynamics.

(As quoted by Gary Taubes) In 2007, Jeffrey Flier, dean of Harvard Medical published (along with his wife) an article in Scientific American called “What Fuels Fat”. In it they quote

“An animal whose food is suddenly restricted tends to reduce its energy expenditure both by being less active and by slowing energy in cells, thereby limiting weight loss. It also experiences increased hunger so that once the restriction ends, it will eat more than its prior norm until the earlier weight is attained.”

If your calorie intake is much less than is needed for a normal human being, all that happens is

  1. You will feel hungry
  2. You will feel irritable and cold (most or all the time)
  3. You will stop being active (not much exercise or exertion)
  4. You will perhaps lose muscle mass

I am sure many of you have experienced this personally 1,2 and 3 if not 4 above.

(Note: There is a particular form of a diet called “Calorie Restriction” which is in vogue. People who have adopted this swear by it and many have lost weight and maintained it. Their blood pressure reduced significantly. But their diet composition also has changed significantly and they also apparently feel cold and perhaps are less active than they were in the past. I will discuss in a future post about diets and comparison of diets.).

In summary, drastically reducing calorie intake is not going to solve the weight problem. You are likely to feel miserable and also may not be able to focus on your job or domestic life.

2. Exercise

What about Exercise? Everyone universally seem to believe that the more Exercise one does the more Weight one loses. The official guidelines are 5 days a week 30 mins a day of aerobic exercise aka treadmill or cross trainer or brisk walking.

Let us look at this in some detail:

A normal aerobic workout of 30 mins for a typical person will burn approximately 250 calories or so. That is the same amount of calories in one single Mars bar or 2 slices of large white bread. If you work out and feel tired or thought you are entitled to an additional helping of pasta or bread or rice or have a pudding or chocolate bar you pretty much have negated all the work done as part of the exercise. It is known that Exercise works your appetite and makes you hungry to some extent.

There have been many studies and trials undertaken to look at the impact of Exercise on weight. In most instances, the effects of exercise on Weight loss were small or marginal in the long term (2 years or more).

Read the following articles..

New York Times

An extract from the article

” And in a just world, frequent physical activity should make us slim. But repeated studies have shown that many people who begin an exercise program lose little or no weight. Some gain”

Another analysis

Why do individuals not lose more weight from an exercise intervention at a defined dose? An energy balance analysis.

Latest article posted in Wall Street Journal (27/Nov/2012)

“New Studies on Older Endurance Athletes Suggest the Fittest Reap Few Health Benefits”

An extract from the article:

” A fast-emerging body of scientific evidence points to a conclusion that’s unsettling, to say the least, for a lot of older athletes: Running can take a toll on the heart that essentially eliminates the benefits of exercise.

“Running too fast, too far and for too many years may speed one’s progress toward the finish line of life,” concludes an editorial to be published next month in the British journal Heart.

What the new research suggests is that the benefits of running may come to a hard stop later in life. In a study involving 52,600 people followed for three decades, the runners in the group had a 19% lower death rate than nonrunners, according to the Heart editorial. But among the running cohort, those who ran a lot—more than 20 to 25 miles a week—lost that mortality advantage.”

Don’t get me wrong. There are a host of benefits of exercise and I exercise regularly (makes you feel better, has cognitive benefits, improves insulin sensitivity, reduces triglycerides , helps recover from injury quicker, increases flexibility, stamina and strength etc.). And I strongly encourage you to exercise regularly (but do the right type of exercise and for the right amount of time) but if your intention is solely weight loss and if you undertake regular aerobic exercise for 30 mins a day, it is unlikely to help significantly in the long run.

Note: There are some special forms of exercise (called HIIT  – High Intensity Interval Training) which are now being advocated for decreasing insulin resistance etc. which in turn should help reduce waistline, triglycerides etc. They will be covered in a future post.

 3. Base Metabolic Rate

Another oft quoted reason is that exercise will build muscle which will increase the base metabolic rate.

Pls see the following article in NY Times about increasing the metabolism

Quote from the article

“Jack Wilmore, an exercise physiologist at Texas A & M University, calculated that the average amount of muscle that men gained after a serious 12-week weight-lifting program was 2 kilograms, or 4.4 pounds. That added muscle would increase the metabolic rate by only 24 calories a day”

To be sure, 24 calories translate to less than 3 gms of Fat reduction a day, if at all.

The amount of muscle that will be built for normal aerobic exercise is much less and hence the amount of energy burnt due to the normal exercise either due to a) increase muscle or b) general increase in metabolism is almost insignificant.


  1. If you eat too few Calories, you will feel hungry and cold and perhaps will lose muscle
  2. Doing regular 30-min exercise solely for the purpose of weight loss is unlikely to work
  3. The increase in metabolism rate due to normal aerobic exercise or otherwise is too small to make a difference to your weight
  4. How much you eat is also dependent on how much you are converting to fat

So, what’s going on then:

The current thinking is that Obesity is perhaps most likely related to improper regulation of Fat metabolism which is mostly due to a problem with hormones. And the problems with hormones mostly are related to diet (and perhaps inter-related to genetic factors to some extent, stress, sleep etc.) but more fundamentally because of issues with our diet.

If our Diet is fine, then the hormones work in balance, the fat metabolism is regulated properly and we will tend not to put on too much weight.

So remember

You do not get Fact because you Overeat. You Overeat because you are getting fat.

For those of you not convinced by the Post read on. I will try to give some examples in real life as well as some lab studies that have been undertaken. These are interesting examples and I urge you to read on..

Go to Part 3



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