How a calorie deficit actually works. Part 3

In Part 1, you learned (or will learn if you haven't already read it) why a deficit of 20% of support is a standard common recommendation and what happens if you eat less, for example, following very low-calorie diets and the unexpected positive effects of such diets.

In Part 2, you learned about the side effects of very low-calorie diets and how metabolic adaptation actually works.

And in this part we’ll talk about the mathematics of losing weight and how a deficit created by reducing incoming calories differs from a deficit created by additional activity.

Is it true that the rate of weight loss can be predicted by knowing the level of deficit?

There is such a popular formula: 1 kg of human fat = 8000 kcal. If we want to lose 1 kg, we need to create a deficit of 8000 kcal. And if we know that our deficit is 500 kcal per day, then in a conditional 2 months we can lose 3.75 kg (500 kk * 60 days / 8000 kk). Would this be a correct guess?

Before answering this question, it must be said that you can find out the exact level of energy deficit by observing changes in body composition. If you have two reliable measurements of body composition (not bioimpedance or smart scales) at least at two time points, then you can find out the level of energy deficit.

Why is a reliable determination method necessary? Because fat and lean body mass can change independently of each other. That same recomposition (decrease in % fat against the background of growing muscles) demonstrates this.

It is also important to note that the density of metabolized energy in tissues (kcal/kg) differs from the BZHU 4-9-4 we are used to.

Thanks to HallWe know that:

Glycogen – 4207 kk;
Protein – 4708 kcal;
Fat – 9441 kcal;
Dry body weight – 1816 kk;

This means that a person who has gained 4 kg of lean mass and lost 1 kg of fat, while becoming 3 kg heavier overall, will still be in an energy deficit, because 4 * 1816 – 9441 = -2177.

But in order to lose one 1 kg of adipose tissue, which most of us usually call a kilogram of fat, we no longer need to burn 9441 kk, but only 8260 kk. Adipose tissue is 87% pure triglycerides, the rest is water and some protein.

Researchers believe that just enough is needed to be “deficient” (8260 kcal) to lose 1 kg of adipose tissue. So yes, the formula is quite workable and reliable, and in research it serves as a guideline on the basis of which assumptions and expectations are based. If participants deviate from the predicted rate of weight loss, this may invalidate the study's results, because the predicted rate is a reliable thing.

But the uselessness of using this calculation in everyday conditions lies in the fact that we do not know the exact level of the created energy deficit, which may cause inaccuracies in forecasting from the discharge “I’ve been maintaining a deficit of 1000 kilos for two months, but I’ve only lost 3 kg.”

This happens, for example, because the calculation method itself is not 100% accurate and even with a detailed calculation there will be errors. Often people are negligent about registering food, because… The method itself is quite tedious. In an attempt to save time, you only end up saving extra pounds.

But an even bigger crutch is that in the energy balance formula there are two variables, and many, when making calculations and forecasts, forget about the second after consumption – energy consumption.

People vary greatly in how much energy they expend. Now we are not considering training, where the level of training determines how many calories everyone can spend, but ordinary household activity. For example, in one study, where people “just sat” in metabolic chambers (in which there is nothing special to do), the difference in energy consumption was 100-800 kk per day. In conclusion, the research used the term “fidgeting,” which can be translated as “fussiness.”

Subjects live in such rooms. There's really nothing to do there. Where does the difference in calorie expenditure come from then?

These are the kind of fussers who can suffer greatly from a calorie deficit, because unconscious and spontaneous activity is primarily reduced to a minimum when fat tissue begins to leave the body.

Less active people are less susceptible to this, because their everyday activity is already mostly purposeful and there is no room to reduce it. Research confirms this. Compensation for energy costs is more pronounced in people leading an active lifestyle, and less pronounced or absent in those who previously led a sedentary lifestyle.

So the calorie deficit on paper may be 2000 kk, but in fact it should not exceed 300 kk. Let me remind you that many people call metabolic adaptation “slowing down fat burning,” which misleads people into thinking that the body is losing the ability to effectively burn fat. But this is not so, he does not lose anything. Simply, with adaptation, the energy deficit becomes smaller, energy requirements are reduced, as is the need to burn accumulated fat to compensate for the deficit. This leads to slower weight loss. By increasing the deficit, the expected rate of weight loss will return.

Despite the reliable formula for calculating the rate of weight loss, as a rule, in practice, the actual rate of weight loss is lower than the calculated one.

Is there a difference between a deficit created by increasing activity or decreasing consumption?

From the point of view of sterile and implausible conditions, there is no difference in weight loss. Whether you create a 500 kcal deficit by training or skipping breakfast, you will lose weight the same.

However, if we move from sterile conditions to real ones, where there is mood, variability in behavior, etc., everything suddenly takes on an individual coloring and more often we strive to control the deficit by cutting down consumption. That's why.

Typically, creating a deficit by increasing activity is not recommended because we do not have an accurate way to measure energy expenditure. Smart bracelets, watches and other equipment cope with this disgustingly; we won’t even consider them.

In addition, we tend to overestimate the amount of energy we spent during training. The level of perceived effort is subjective and cannot serve as an objective assessment of the effort expended. Beginners who feel very tired after a workout may not actually be able to expend much energy due to low performance and fatigue. However, even experienced athletes are subject to inadequate assessment.

Another increase in conscious activity (any training, any purposeful activity, for example, for the purpose of spending additional calories) can affect all remaining activity (everyday).

Many people subconsciously reduce their energy expenditure, especially their level of physical activity without training (household), after aerobic training, so that additional training does not lead to the expected fat loss; sometimes additional aerobic physical activity does not increase total daily energy expenditure at all [2, 3, 4]

A large systematic analysis showedWhat

“The typical person's energy compensation averages 28% through lower basal energy expenditure; this suggests that only 72% of the extra calories we burn from extra activity are converted into extra calories burned that day”.

And another set the average at 18%.

And some people have much more adaptive metabolisms than others. Both analyzes showed that in some people, aerobic training compensation was greater than 80%.

Although, as noted above, people with a sedentary lifestyle are less susceptible to such adaptation, so increasing their activity will definitely help them lose weight.

Nevertheless, it is better to use training both during and after weight loss. Strength training will help maintain muscle mass, which the body may also lose during weight loss. With training, it is easier to maintain body weight in the future after losing weight. Exercise also helps many people control their appetite.

As noted in one studya deficit of 400 kcal due to exercise on a bicycle ergometer did not lead to an increase in appetite in participants, while a deficit of 400 kcal due to a decrease in caloric intake did.

Although, this may not be due to the way the deficit is created per se, but to the fact that training reduces appetite through the activation of the sympathetic nervous system – the one responsible for the fight or flight response. Thus, physical activity activates a response that discourages food intake, thereby improving hunger and appetite control while dieting.

To summarize, it can be argued that an increase in training activity can be fully or partially compensated by a decrease in household activity, which will not lead to the desired rate of weight loss. And the lack of accurate methods for determining energy expenditure leads us to the conclusion that using increased activity as the only tactic to create a deficit will be a very ineffective method for sustainable and long-term weight loss (although still very beneficial for overall health). However, it is better to use exercise during and after weight loss (for life), as it can facilitate diet control by suppressing hunger, maintains muscles and protects them from breakdown, and can still create additional energy expenditure if it is not compensated for. and once again – it is very good for health.

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