What causes weight loss? The basic thing, explained using Science

Well the answer here is complicated and controversial, there are many theories which support both, but we will describe here what most real life situations and practical outcomes. We are convinced by health websites advertising to exercise regularly and not to worry about your diet, or the other way around by dietitians and medical websites selling all sorts of medicines and diet plans, we do not support any of these. You can gather information by yourself from various sources and scientific journals available. Internet is a great source of data. By combining all sorts of scientific studies, experiments, articles and we deduce this knowledge.health

As per many studies you might find, we must understand are conducted in controlled situations, what it means, that if the impact of exercise is studied, food intake is set as constant. When food effect is studied physical work is kept constant.

fat energy or surplus calories stored as fat in the body = Intake – Calories spent

For basic body functions= 2000 cal as per US Agriculture Dept.

As there are many theories, we assume it 2000 cal, the exact number doesn’t matter. So, out of 2000 cal, basal metabolic rate is at an average.
For Women: BMR = 655 + (4.35 x weight in pounds) + (4.7 x height in inches) – (4.7 x age in years) =1,493 calories
For Men: BMR = 66 + (6.23 x weight in pounds) + (12.7 x height in inches) – (6.8 x age in years)=2,052.9 calories
Average consumption men = 2640 , women = 1780, the BMR is consumption at rest, this intake is due to average daily physical activity.

Its easy and simple, you have to intake lower calories or spend. We have .45kg or 1 pound = 3500 cal

Workout only Method

Amount of calories burnt with constant running 30 min 10kmph= 250-300 calories

So you would have to run approximately 1hr daily for 13 days to reduce 1kg weight at 10kmph, assuming you wont eat more than usual after this rigorous workout. It is seen that more workout causes more consumption in real life. A less intense workout will not have a significant effect on intake.

Average meal is 500 cal, snacks is 200 cal. A mere snack will cost you 200 calories, 30min more workout.

Only Diet Method

Now we assume that we consume all calories we eat, no workout and no exercise.

Now a cut-down of 700 cal a day, 1 meal and snack will take approx. would take it significantly lower time to reduce weight, 10 days.

The truth is, its easier to manage this situation and control your intake than previous one , but eventually your body feels too tired and basic functions also reduce BMR reduces and causes health risk.

Moderate exercise and Diet

The conclusion of our study is that 2nd method is easier and more effective, however might have health risks and lower your metabolic rate, low physical activity also causes other health problems. A moderate exercise and balanced diet is what it takes to really get what you want.

So what do we mean by moderate, we would say about 30 min running or equivalent.

Since calories are balanced we assume that average calories consumed – spent = 700 cal (same as case 2 as workout will have effect on your diet)

this is safe option for your health and average time to reduce weight is 10 days for 1kg.

Extreme weight loss

To reduce weight at a faster pace, there is only one way, to significantly reduce diet. Let us take a moment to look at the situation, we say about 1000 cal a day

Workout required  for 1000 calories = ~ 3 – 4hrs of running  or equivalent with controlled diet

Diet plan reducing your current consumption by a 1/4, seems a little easier. With controlled exercise this can be achieved more easily.

So what we all want is achieved by moderate or no exercise and a controlled diet, however a moderate exercise would help.

Note: This is how celebrities reduce significant amount of weight in such less time.


The best method is 3rd for controlled and healthy way, i.e light exercise and controlled diet, as exercise is more important than weight loss, it prevents health risk, maintains your metabolic functions, fights diseases and maintains overall health of your body, you can age well and feel more good about yourself.

When it comes to weight loss, we have concluded from the facts around the web, researches and experimental data available on several studies that diet contributes much more significantly to weight loss than physical activity.


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