We understand that many people believe 1200 calories is a proper calorie deficit to lose weight; after all that is the classic ‘diet’ intake level that is prevalent amongst diet culture.
However, the human body has basic energy demands to support optimal health, and for grown adults, the 1000-1200 calorie intake level does not support those needs, and in turn, can inflict a lot of stress on the body.
In this article, we want to explain and expand on each of the ways that the body requires energy to display why we need to be fueling our bodies with way more than 1200 calories!
What is Energy Expenditure?
To understand energy expenditure, it's important to understand that our body creates energy in the form of heat to provide fuel for everything we do in a day. This includes physical functions such as breathing, circulating blood, digesting food, or exercising.
Energy is measured in calories and our Total Daily Energy Expenditure [TDEE] is the amount of calories that we burn daily, which is largely based upon your activity level, types of food you consume, and your body composition. Once we understand this, then we can balance our energy intake with energy expenditure to either maintain weight, lose weight or gain weight.
There are obviously MANY ways that we burn energy, but the only ways that we can provide the body energy is through the foods and drinks we consume. At a macro level, energy comes from protein, fats, and carbohydrates, and alcohol if included in your diet.
Energy expenditure is the sum of the basal metabolic rate [BMR], the thermic effect of food [TEF] and thermic effect of physical activity [TEPA]. Let’s break each one down further to understand more:
1) Basal Metabolic Rate is the amount of energy the body burns at complete rest each day. Basically, if you were to lay in bed all day, it is the number of calories required for the brain and central nervous system, heart, kidneys, liver, lungs, muscles, and skin to function properly (SOURCE). This can be extremely hard to measure with 100% accuracy, but utilizing a body-fat scanner, like an InBody machine or a DexaScan can get most people a pretty good idea.
The things that mostly determine this are your age, height, weight, and lean muscle mass. In one study, they measured that females have, on average, a basal metabolic rate of about 1300 calories, and males were about 1900 calories . Then we factor in the other demands from the thermic effect of food, non exercise activity and exercise.
2) The thermic effect of food is the energy required to break down, digest, metabolize and absorb food. The process of chewing and digesting food requires effort and energy from your body.
There is an increase in the metabolic rate after consuming meals and evidence suggests that TEF is increased by larger meal sizes (as opposed to frequent small meals), and higher levels of protein and carbohydrates, as fat requires the least amount of energy.
You may have heard that certain foods burn more calories, and that is true to an extent, but don’t be fooled by the “metabolism boosting foods” as they don’t burn as many calories as you may think.
TEF only makes about 5% to 10% of daily calorie expenditure. In a simple example, if you consume 2,000 calories a day, about 200 of those calories would get burned through digestion and absorption.…so it is not an eat more and burn more type of situation like Shop N Save [their motto is the more you shop the more you save - but you also spend more right??]
Let’s break this down by thetype of foods that require more energy to be digested and utilized for energy.
Protein has the highest TEF as proteins are more difficult to digest and support the growth of muscle mass, especially if you strength train. Research has shown that the TEF for protein is 20–30% since more energy is lost during the process of digestion (source). So, for example, if you have 100 calories of chicken breast, you would burn 20-30 calories in the digestive process, leaving you with about 70-80 net calories. Note: we do not recommend factoring this into your overall daily intake the way some people factor in net carbs. If you’re struggling to consume enough protein, you can always supplement with a high quality protein powder such as CLEAN!
Foods with relatively low thermic effects include fats and most carbohydrates, since carbohydrates, especially sugars, cost the body relatively little energy to digest and metabolize.
The TEF for carbohydrates is about 5-10% and fats are only 0-3%. So, if you’re looking to maximize energy expended with TEF, utilize higher protein foods.
Additionally, the processing of food also matters! Research has proven that consuming whole, unprocessed foods requires more energy compared to processed foods.
In one study, participants were separated into two groups and given either “whole food” (minimally processed) or “processed food” meals of the same calorie value. In this case, they used cheese sandwiches, with the whole food sandwiches being made of multi-grain bread and cheddar cheese while the processed sandwiches were made with white bread and processed cheese products (source).
The results were pretty amazing! What they found was that while the two meals felt equally filling, there was a huge difference in terms of how much energy they burned in the process of digesting the meal. The whole food group burned almost 50% more energy during the process of digestion, and this meant that they absorbed a smaller number of net calories. Another reason to opt for whole, unprocessed foods!
3) Thermic Effect of Physical Activity [TEPA] - This includes Non Exercise Activity Thermogenesis [NEAT] and Exercise Activity Thermogenesis [EAT] and accounts for the rest of our daily energy expenditure.
So, as you can see, the body expends energy in many ways! And if we consider all of these factors, we may need to rethink our intake goals, both for fat loss and for maintenance. Meaning, we don’t want to over restrict calories in an effort to ‘lose weight faster’ as that is only going to create more stress on the body.
When we are highly stressed, our stress hormones rise, including cortisol. This can impair digestion and slow down metabolism! One study comparedtwo groups of females that ate the same high calorie meal, but those who reportedly struggled with stress the previous day expended 100 LESS calories than the control group. This is because higher stress = lower fat oxidation and higher insulin production.
Another factor to consider is that poor sleep has been shown to slow metabolism and reduce energy expenditure by about 300-400 calories per day. However, because of the hormonal impact on our hunger and satiety hormones we feel hungrier, less satiated by food, and often crave carbs and sugar when sleep is inadequate. Not a great combination when we are aiming to lose weight - so sleep should also be a priority! You can learn more HERE about how our sleep and circadian rhythm impacts our weight.
So, while it is necessary to balance energy intake with our goals, we want to do so in a smart way! Rather than dropping calories drastically, we recommend a more moderate calorie deficit such as 20-30% of your maintenance intake - i.e. If your maintenance intake is estimated to be 2200 calories, then we recommend a fat loss intake of about 1540-1760 calories - not 1200 calories as that would create a 1000 calorie deficit.
If we go too far beyond a moderate calorie deficit (~20% of maintenance), the body actually starts to go into somewhat of a ‘conservation mode’ and will find ways to store energy instead of burn it. This means we will start storing fat instead of burning it because the body sees it as a famine state. We have to outsmart the body by decreasing in a sweet spot to allow it to feel safe enough to drop body-fat while still keeping up with our other daily need’s functions - which research has shown is about that 20-30% decrease compared to maintenance.
Remember this is not all about calories in, calories out as we have learned there are a lot of variables that need to be considered and as we have learned, not all calories are equal :)
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