Energy is measured in calories. One unit of energy is one calorie. We continuously spend calories (energy) to run vital functions like breathing and circulating blood around. We obtain all our calories from the food we consume, and meet our energy requirement with these calories.
The terms energy and calorie are used interchangeably in this chapter.
How are calories spent?
We constantly spend energy (calories) for vital functions such as respiration, digestion of food, production of urine, and maintenance of the blood circulation. This calorie expenditure is not under our control and will take place whether we want to or not. These calories will be spent whether we are active or totally sedentary. A very large portion of our daily calorie expenditure is through this route. The number of calories spent through this route depends on our body weight, height, gender and age, and is known as basal metabolic rate (BMR). The BMR can be calculated by a simple formula called the Mifflin St Jeor equation.
What makes us gain weight?
Why is it so difficult to lose weight?
How to reduce body weight?
What is the relation between physical exercise and weight gain?
Calories are also spent when we carry out any physical activity such as walking, exercising, talking and chewing food. This calorie expenditure is under our control. By increasing our physical activity we can increase our calorie expenditure, and decrease our calorie expenditure by reducing physical activity. For an average person with modest physical activity, not many calories are spent through physical activity.
Our total calorie expenditure each day = BMR calories + calories spent by physical activity.
An average person expends about 1800-2000 calories each day. The calorie expenditure by physical activity is pretty small – about 200-400 calories. Most of the calories are spent through the BMR route which is about 1500-1800 calories.
Source of calories (energy)
Our one and only source of energy is food. Every item of food and beverage has calories. Water is the only substance which has no calorie.
Our body processes whatever we eat, uses up the calories that are immediately required and stores the remaining energy. The excess calories from fat are stored as fat, carbs are stored as glycogen in the muscles and liver, and protein is stored in the muscles. We have an instant and perpetual access to this stored energy – we are continuously depositing and picking up calories from this store.
This system works very well to our advantage. Our intake of energy is irregular because we eat at uncertain intervals but we need a steady and continuous supply of energy. This requirement can be easily met from the stored fat, glycogen and protein.
The route to overweight and obesity
The biochemical and biological processes that govern our body weight are very complex and not fully understood. Nonetheless, it is now clear that excessive calorie intake, and too many carbs in the diet play a key role in producing overweight and obesity.
1. Excessive calorie (food and beverages) intake:
The state of calorie balance (calories intake vs calorie expenditure) absolutely determines our body weight. If we regularly consume more calories than what our body spends, we will gain weight and become overweight and obese. This solid law of nature holds true for whichever diet is consumed.
2. Too many carbs in the diet:
Although calorie balance is completely and totally responsible for what we weigh, excessive consumption of carbs also plays a very prominent role in producing overweight and obesity.
Over the past few decades, fat in our diet has been so severely demonized that we have become wary, and have reduced fat to the bare minimum. Consequently, carbs are now form a dominant part of our diet, more than 60% of food consumed consists of carbs. The carbs are mostly simple and refined such as sugar, glucose, white rice, white bread and buns, noodles and pastas from refined flour, sweeteners such as high fructose corn syrup, and processed foods like corn flakes and pizza.
Excessive intake of refined carbs leads to overweight and obesity. This is how it works:
Excessive refined carbs in our diet leads to the secretion of large amounts of insulin. The refined carbs are rapidly broken down to glucose. Over the course of a few hours after a meal, the insulin helps the cells absorb glucose, and it also moves the circulating fat into fat cells. The large quantity of insulin ensures that most of the circulating fat is stored away in fat cells.
When most of the circulating fat gets stored away, very little is left in the blood for supplying energy. Our brain senses a shortage of energy, and sends out two signals: the first signal is to conserve energy, so the stored fat remains locked in the fat cells, which contributes to weight gain; the second signal is to acquire energy, causing the ‘hunger signal’ to be released. The hunger signal promotes food intake which inevitably means more carb consumption, and the whole cycle is repeated.
Regular consumption of large amount of carbs results in excessive secretion of insulin, fat storage, and increased food intake. The net result: overweight and obesity.
Once we become overweight, we are set on the path to steadily gain more weight. This is because overweight causes insulin resistance. The circulating insulin is unable to process the blood glucose. Our body responds by secreting progressively larger amounts of insulin to overcome the resistance to insulin. Because of the large amount of circulating insulin, there is a sustained storage of dietary fat in fat cells – leading to continuous weight gain.
If simple and refined carbs are eliminated from the diet, the situation changes completely. Studies have shown that a very low carbohydrate diet with no refined carbohydrates has a very favorable effect in reducing weight and maintaining this over time. In such a scenario, very little insulin is secreted, and all this insulin is used up to process the glucose in the blood. There is no excess insulin available to push the fat molecules into the fat cells, and the fat remains in the circulation to provide energy. There is a plentiful supply of energy so the brain does not send any signal to conserve the energy nor does it send any ‘hungry signal’. Net result: fat is not stored and there is no increased demand for food intake.
Why is it so difficult to lose weight?
Most of us who wish to shed weight do so by cutting back on food, primarily fatty food: we adopt a low calorie (i.e. less food), low-fat diet. We manage to lose a few kilograms but within a few months are back to where we started and some more.
There are three factors that make it difficult to lose weight:
a) After a few weeks of enthusiasm, we lose the passion and motivation for the low calorie (less food), low fat diet.
b) As the weight gradually decreases, the BMR also correspondingly declines, and our calorie expenditure progressively decreases. So, in order to continue losing weight, the intake of calories (food and beverages) has to be reduced gradually. This is difficult to implement.
c) A low fat diet is inevitably high in carbs. Any attempt to try to lose weight is doomed to failure when there is a surfeit of carbs in the diet. By severely restricting calorie intake we will manage to lose some weight for a while, but the powerful role of insulin will ensure that within a few weeks or months, we will not only have regained all the lost weight but will end up gaining some.
A simple guide to reducing weight
Scientific studies have consistently shown that although a negative calorie balance (consuming fewer calorie than what are spent) is the only consideration that produces weight loss, there is another factor that also plays an important role. This is the quantity of carbs consumed, particularly simple and refined carbs. Cutting out simple and refined carbs helps lose weight without the need to focus on calorie intake. This is convenient because it is absolutely impossible for most of us to track our calorie consumption, but we can easily stop consuming certain groups of food such a simple and refined carbs. Modest physical activity has many health benefits, but does not have any significant influence on our weight.
Eliminating simple and refined carbs will inevitably mean that the diet will be high in fat and protein. When we eat, once the stomach is full, the fatrich diet will send out a message of satiety. This is the signal for us to stop eating. It is nature’s way of ensuring that we do not consume too many calories. Failure to heed the message of satiety, will result in overeating and weight gain, even with a low carb diet. Several hormones such as insulin, gherlin and leptin play a critical role here by establishing a calorie balance in favor of ideal body weight.
This weight reduction plan will be effective only if simple and refined carbs are truly discontinued. Unrefined whole grain carbs such as whole wheat products, brown rice, bajra, jowar, corn, sattu, ragi, and dal have a subdued effect on insulin and other hormones, and therefore, it is perfectly OK to consume them in moderation.
Besides reducing the body fat and body weight, a low carb diet confers many other advantages. A low carb diet reduces triglycerides (bad lipid), increases the ‘good’ HDL-cholesterol, and decreases the overall number of toxic small, dense LDL, the type that promotes heart disease. Saturated fats, part of a high fat diet, make the LDL particle size large. The net effect: reduced risk and reversal of heart disease
Moderation is a very subjective term. What is ‘moderate’ consumption to one person is inadequate or excessive to another. The way to assess whether our food intake is moderate, is to check our body weight regularly. If the weight is creeping up, we are consuming food (and calories) in excess.