How to lose/gain weight: Part 1

Losing weight is often considered a daunting task. When you think of losing weight, all you can imagine are strict diets, cravings, low fat/low carb diets, “health foods”, starvation and inevitably, failure.  

There is a science behind weight loss. And by following what I’m going to tell you, losing weight will become a breeze.

Remember reading about the laws of thermodynamics in high school? The first law of thermodynamics states that energy can neither be created nor destroyed; rather, it transforms from one form to another.

This applies to us too. We get energy from the food we eat. This energy is usually measured in terms of kilojoules or kilocalories or Cal. 1 Cal (or 1 kilocalorie) =4.184 kilojoules. Whenever you see calorie labels on food items, they are almost always in terms of Cal or the kilocalorie.

BMR and TDEE

Depending on a person’s height, weight age and gender, their daily caloric expenditure varies. If you think about it, it makes sense. A 5’ tall, 45kg woman will naturally have a lower caloric expenditure as compared to a 6’ 2”, 100kg man. The man will have to spend more energy throughout the day to move himself around.

Using data from tens of thousands of people, we have an average value of the caloric expenditure of a person based on height, weight age and gender. This caloric expenditure is called BMR (Basal metabolic rate). Keep in mind that this is the amount of energy spent per day when your body is theoretically at rest. So if you lie in bed all day, doing nothing, you will burn calories equal to that of your BMR. You can check your BMR using this.

A more practical calculation of your daily caloric expenditure is TDEE (total daily energy expenditure). This takes into account your daily activity levels in addition to height, weight age and gender. A person who moves around a lot during the day will have a higher TDEE than someone working a desk job, even if they are of the exact same height, weight, age and gender. You can check your TDEE here.

So now you know your TDEE. As I was saying about the law of thermodynamics, energy can only be transformed from one form to another. So the calories you eat are either burned off during activity or stored in the body as fat/muscle. So eating a surplus of calories above your TDEE causes weight gain while eating a deficit causes weight loss. Of course, this is oversimplifying what exactly happens in the body, but for the sake of understanding this is the best way to put it.

How do you calculate your calories?

This requires effort in the beginning. It’s not something you have to do to lose weight; rather if you do it correctly, you can be sure of getting results.

You’ll need a food scale and a calorie counter app for this.

1 gram of carbohydrates has 4 Cal (or kcal).

1 gram of fat has 9 Cal (or kcal).

1 gram of protein has 4 Cal (or kcal).

Measure the food you eat. Enter the weight into a calories counter by looking at the food’s nutrition label. If the particular food you ate doesn’t have a nutrition label, then you can search the database to get something close.

Remember, the nutrition label on many food items probably isn’t too accurate. But it’s better than not knowing how much you’re eating. So you don’t have to hit your caloric goal to the dot every day. Just having an idea on how much you should be eating and how much you are eating every day.

 In this part I've covered the basics of the science behind weight loss. In my next article, I'll be talking about how you can use this knowledge to help you lose weight.