Weight loss refers to a decrease in your overall body weight from muscle, water, and fat losses.
Fat loss refers to weight loss from fat, and it’s a more specific and healthful goal than weight loss.
However, it can be difficult to know whether you’re losing weight from fat or muscle.
Your bodyweight can be divided into two main categories — fat mass and lean mass.
Fat mass is exactly what it sounds like — our total body fat levels. Lean mass is anything that’s not fat mass, and can be further broken down into bone mass, muscle mass, water, and organ mass.2
Here’s where some of the confusion lies. Very few people purposely try to lose lean mass, but are more interested in the fat mass side of the equation. However, if we only use the scale to look at weight loss, then there’s no indication as to whether we have lost fat, muscle, or something else.
Weight loss doesn’t discriminate on what’s lost. It’s purely a numerical measure and doesn’t take into account the quality of what’s lost or gained — plus it can be quite easy to trick the scale. Just by switching from a high-carb to a low-carb diet you can see a dramatic reduction in weight loss. That’s because 1g of stored carbs holds about 3g of water in the body. 4
This is one of the main reasons why when people go on a low-carb diet, they see almost an instantaneous drop in their weight, but it is important to remember that the change has nothing to do with fat loss.
There are other things that can affect weight fluctuations on a daily basis — all of which are normal. Hormonal fluctuations, varying sodium intake, different amounts of dietary fibre, and food sitting in the gastrointestinal tract.
All of these can cause your weight to fluctuate, so when you see these changes on the scale, is it weight or fat that’s gained or lost, and should you be focusing on weight at all?
Everyone has a certain amount of body fat. This fat is often expressed as a percentage of their total body composition — for example, 16% body fat.
Women tend to have more body fat on average than men. One of the reasons for this is that women need to maintain a higher level of body fat for the reproductive system. Men also tend to have more lean muscle mass on average than women for a given weight, which can lead to a lower level of body fat.6
A male athlete can have a body fat of anywhere from 7% to 13%, compared to the female equivalent of 12% to 20%.6 Fit and athletic men can be anywhere from 12% to 17%, and females 17% to 24%. An average healthy man can have up to 24% and women can be up to 30%.6
If fat can be lost, it must be stored. Excess fat is stored in the body’s fat cells which are called adipocytes. This is where we get the term adipose tissue, which literally means fatty tissue.
The most common types of body fat (adipocytes) that are spoken about are subcutaneous fat (the fat between the skin and the muscle), and visceral fat (the fat around the organs.) There are others, but these two are the ones most responsible for health and appearance. Fat loss is the breaking down and reduction of these stored adipocytes.
We can’t choose where we want to lose fat from, and there’s no special protocol to help spot reduced body fat. This means you can’t exercise a specific area that you would like to lose fat from and hope it works. Unfortunately, if you want a flat toned stomach, sit-ups alone won’t help you lose the weight — but a calorie deficit will.