Before we get into this post, this is not meant to sway you one way or another, or to tell you that your goal is incorrect and you should change it. This post is meant to be informative and help clear the difference between weight loss and fat loss.
There is nothing wrong with just losing weight. There is nothing wrong with wanting to lose fat. There is nothing wrong with wanting to change your body for YOU. There is nothing wrong with keeping your body just the way it is.
Now that we have that out of the way: weight loss and fat loss are not the same thing.
Most people say I want to lose weight, however what they are probably meaning is that they want to lose fat.
TL;DR:
Scale weight = your total body weight.
Total body weight = (fat mass + lean mass) x gravity.
When you lose weight, without prioritizing some key factors, you lose weight fairly evenly between fat and lean mass.
Due to this, most people aren't actually all that content with the end result of weight loss as they did not achieve the more defined physique they were looking for. They feel like they need to lose more weight than their original goal to achieve their dream physique, and are more likely to gain it back quicker.
Longer explanation:
Total body weight is your gravitational pull towards the center of the Earth.
Fat mass is part of what makes up your total weight. Your fat mass is composed of essential fat and stored fat. Essential fat is necessary for normal bodily functions.
To keep it simple, the other aspect that makes up your total body weight is your lean mass. Lean mass is your muscles, bones, organs, blood, water, etc.
When you lose weight without focusing on your protein intake, resistance training, and/or have too high of a caloric intake deficit, the weight that has been lost can be relatively even between lean body mass and fat mass. Your body does not prioritize the weight coming off from just fat unless you help stimulate protein synthesis.
Therefore your scale weight is going down (weight loss) but you are probably not seeing a big change in the mirror, the way your clothes fit, or body circumference measurements. This is because fat is less dense than muscle.
I addressed this on my blog post how and where to take body measurements, so I'll only quickly review it here.
1lb of fat = 1lb of muscle
However, that same 1lb of fat takes up more room (volume) than 1lb of muscle.
On the scale they register the same but visually, or through a circumference measurement, they are significantly different.
So if your goal is to "tone up" your body, you want to decrease your fat mass as you will hang on to muscle and have a more defined appearance even if the scale weight was not significantly reduced. If you do not prioritize fat loss, your scale weight will go down and you will be smaller than before but you will not have a lot of muscle tone. This can be frustrating to many as you weigh less but you are still not as defined as you expected you would be once you reached your goal weight.
Here is another kicker as to why you should prioritize preserving your lean body mass during weight loss, even if your goal is not to have a more defined physique: research has shown that people who lose excessive lean body mass are more likely to gain back the weight and then some, damage their metabolism, and create negative psychological changes.
This study found that severely restricting calories (55-60% calorie reduction of daily maintenance calories) of already lean men resulted in the subjects gaining weight beyond their original weight until their lean body mass equaled the same as it did at the beginning of the study once they stopped restricting calories. Key words: lean body mass equaled the starting point, not total body weight. In other words, the subjects lost a significant amount of lean body mass and fat mass during a severe calorie restriction period and when they were allowed to eat whatever they wanted again (go back to their lifestyle pre-dieting) they gained weight back mostly in the form of fat. This weight gain did not stop until their lean body mass reached its original point, but as protein intake and resistance training were not a priority after their diet, most of the weight gain came from fat. This is the same phenomenon as someone who goes on a fad diet, quickly loses a significant amount of weight but then gains it right back and then some. This study also highlights the negative psychological changes that occurs on these subjects from the extreme calorie reduction.
Another study, on obese subjects who participated in the biggest loser, found that the more weight was lost the more likely they were to regain it because the weight came off too quickly (30 week) through a high calorie restriction. This quick weight loss led to slower metabolisms and increased levels of hunger due to hormone changes.
So how to you ensure you are losing fat mass and at the right pace?
To preserve your lean body mass during weight loss and therefore lose scale weight from mostly fat, protein synthesis needs to be greater than protein breakdown. You can achieve and optimize it through these factors:
Protein intake: consume 0.8-1.1grams/lb of bodyweight on a daily basis
Resistance training: priotiorize strength training through a well developed program
Moderately reduce caloric intake: determine maintenance calories and reduce by 10-20%
How do you know which one you should prioritize?
This is a subjective area and you are the only true person that can answer this for yourself.
Determine what is most important to you: becoming smaller by scale weight definition or having a more toned physique?
If you are someone how has been wanting a flat, defined stomach then fat loss is for you. If you are someone how wants to be lighter, then weight loss is for you.
What do different body fat levels even look like?
Here is quite possibly the most common image when you google "what do different levels of body fat look like?":
*I would like to just comment on my level of annoyance that the images of females are not ordered the same as they are for men.
Reminder, this is just generalization. Someone who has a low weight scale could still have a higher body fat percentage if they do not priotiorize muscle development. So two people of the same height could both weigh 150lbs but one could look significantly more toned and smaller than the other if they have prioritized muscle development.
Potential negative effects of high body fat reduction:
Above I mentioned that fat mass is a summation of essential fat mass and stored fat. Essential fat mass is what we require as humans to keep our bodies running normally.
For example, when a woman's body fat percentage goes too low she will lose her menstrual cycle as she has disrupted her reproductive system by not having enough body fat. One study has shown this to occur between 17-22% and another 26-28%. There is a lot of data on this out there but not a conclusive number, rather a recognition that this varies from woman to woman. So if you notice that your cycle begins to become irregular or goes away after dieting, you should take a step back and reconsider continuing on your body fat reduction.
So while having a chiseled physique can be desirable, it can come at the expense of your heath. Take this into consideration before trying to reduce your body fat too low.
Reminder that we are all individuals with our own genetic compositions and our own individual needs. Striving for a physique determined by societies standards of beauty can be detrimental physically and mentally.
I hope that you found this informative. Do not hesitate to comment below if you have any questions!
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