When it comes to health and aesthetics, the question between weight loss vs fat loss, comes up a lot.
Weight loss is a drop in body weight, which can be from any bodily constituent such as; muscle, water, fat, urine, or faecal matter. Fat loss is a reduction in body fat stores, this has nothing to do with the scale weight. Someone can see the scale weight increase, through water and muscle, but still have lost body fat.
Difference between bodyweight and body fat
Bodyweight is comprised of various parts.
- Lean mass
Knowing theres more than one element to your bodyweight, will help you understand what’s going on better.
What is body fat?
Body fat comes in 2 different forms: (3)
- Visceral fat
- Subcutaneous fat
Visceral fat is the fat that surrounds your organs. This is the fat that’s considered “bad fat”. It tends to accumulate around your stomach. Oftentimes, known as the “beer belly”. (4)
This is the more visible fat, which sits under the skin. This fat is less risky to your health, it’s associated more with women. It’s fat, which sits in and around your lower body. (5)
The thing is, women need more fat than men, for reproductive purposes. Hence why they store theirs, in less harmful areas. (6)
This is why it’s not technically healthy for women to be obsessing over getting shredded abs. Body fat is very important and has been for millions of years due to evolution. But that’s a post for another day.
Lean body mass
Then we have lean body mass, this is what else constitutes bodyweight.
- Food and waste volume
What does this mean?
This means when you are losing weight. It’s more than just fat. Therefore, when you are weighing yourself, the scales doesn’t tell the whole story.
For every gram of glycogen you hold, your body holds another 3 grams of water (7).
The average person holds 600g of glycogen, which comes with 1800g of water. That’s 2.4kg altogether, or 5.28 lbs of extra bodyweight. (8)
This is why, when people start a new diet or go low carb, they lose 6lbs in a week. What’s happening is, their glycogen levels have decreased and they’ve lost a lot of water.
This is why you gain 6lbs overnight when you stop dieting. This isn’t fat gain, this is water and glycogen. (9) Unfortinaelt slimming clubs don’t educate their members this. This is why when they see the scales fluctuate they get disheartened.
Some people are more muscular than others. For instance my BMI is “overweight”. But my body fat levels are lower than the average male.
When it comes to losing weight, you do not want to lose any lean muscle mass. However a lot of weight loss diets cause muscle loss, as theres no mention of eating enough protein or resistance training. A crash diet, with little protein and no resistance training will lose you a-lot of “weight”, but if a lot of that is muscle, it’s not going to do you any good.
Having adequate muscle is very important, especially as we age. It prevents the risk of developing sarcopenia, manages blood sugar, makes you look good and makes everyday life easier. (10)
Water can fluctuate for many reasons. Going to the toilet can lose you a pound. The menstrual cycle can fluctuate water by 3-6lbs during the 4 weeks.(11)
If you’ve eaten a salty meal, like a takeaway, your body will hold more water. (12) This is your body trying to sustain equilibrium.
When boxers go for weigh-ins, they manipulate the amounts of water they hold in their bodies. This can be done by various methods of dehydration. Some can lose up to 12lbs of water before a fight.
This shows with water alone, there’s a massive variance between weight loss vs fat loss.
This also gets overlooked.
If you’ve eaten more food than usual, you’re going to weigh more. Food is heavy, thats why you weigh around 3-5lbs more in the evening, than the morning.
That is part of the reason you gain 7lbs after xmas day. It’s not all fat. The majority is food volume and water.
Why is fat loss more important than weight loss?
Unless you’re an athlete making weight for a sport. You want to be losing excess body fat, without losing muscle.
Muscle as I mentioned earlier, has so many benefits. It would be absurd to want to lose it.
Excess body fat on the other hand, can be harmful to your health, if you’re carrying a lot.(13)
Having more natural muscle, on the other hand, will have the complete opposite effect. Though it is harder to obtain, it makes life far more easier and enjoyable.
Though the scale is a great tool for fat loss, it is only a tool. What the scale is telling you about your weight, maybe masking what is happening with your fat loss. If you’ve been eating in a calorie deficit, but ate a very salty takeaway the night before, though you’ve lost fat, you might have gained 2 lbs in water weight. And what I know a lot of people that go to slimming clubs will do, is feel like they failed and binge. when in actuality, they did lose fat, but water masked the scale weight.
How to lose fat, without losing lean mass?
A lot of people, when trying to lose fat, tend to lose a lot of muscle too. This ends up with you looking emaciated.
To lose fat without losing muscle mass, there are 3 fundamentals to follow.
- Calorie deficit
- Resistance training
- Adequare protein
Nutrition is critical. The only way to lose fat is to eat fewer calories than you burn. The amount of calories dictates what your bodyweight will be. (14)
If you eat more calories than you burn you gain weight.
If you eat less calories than you burn you will lose weight.
If you want to know more about the science of a caloric deficit, I have you covered “How to be in a calorie deficit“.
If you’re eating few calories than you burn, you will lose fat regardless of what the scales tell you.
To sustain your muscle, look to do some strength training at least twice a week. (15) I can’t state how important resistance training is for fat loss. You either use your muscles or lose them. Your muscles need resistance. When dieting your body will assume your muscles are not needed and will burn them for energy, otherwise. (16) Unfortunately most people don’t do any resistance when trying to lose weight.
What we are looking to do, is only use fat for energy. Then we can preserve and build some new muscle tissue.
Rest assured, it’s totally normal for scale weight to increase when you begin weight or resistance training. One reason is increased water retention. (17) This will be due to you drinking more water to rehydrate your workouts. Resistance training also creates muscle tears, which also hold more fluid. (18) This is another reason why slimming clubs, tell members not to resistance train, as it will affect scale weight…
You must eat adequate protein to lose fat and not muscle. By eating enough protein. you ensure sure your body is not breaking down any muscle. That way your body will be going to its fat stores for energy instead. (19)
Aim for 1.6 – 2.2g of protein per kg of your target bodyweight. (20)
So if you are aiming to weigh 80kg, aim for at least 128g of protein, per day. But if thats too much, start a lower amount and slowly build your way up.
How do I know if I’m losing fat?
So we now know the various reasons, that there’s a difference between weight loss vs fat loss. Let’s see how we can make sure the only weight being lost, is fat.
When looking to measure fat loss, these are the metrics you want to keep an eye on.
- Scale weight
Photos don’t lie. The frequency of how often you take them is up to you. I recommend you take them once a month. A front, back and side view will paint you a strong picture. Make sure to take them at the same time and place of the day.
Make sure the lighting conditions are the same.
Photos are an effective way of noticing the difference between weight loss vs fat loss.
You might weight the same the next month. But if you look leaner, you have lost probably fat.
I recommend taking a waist measurement every two weeks.
As the ‘bad’ fat accumulates around the waist, if the waist decreases, you’re heading in the right direction.
Current evidence suggests, that if your waist size is less than half your height, you are at a healthy body fat percentage. (21)
I’m 5”10 (178cm) and my waist size sits between 30”-32” (76cm-81cm).
As you can see my waist is well under half my height, but my BMI sits between 26-27, which is ‘overweight’.
Regardless of scale weight if your clothing is fitting better. I can guarantee you’re losing fat. For me this is the ultimate indicator of fat loss.
When clothes get very loose around the waist, that means you’re losing fat exactly where you want to lose it.
Don’t throw your scales out yet, that’s dumb advice.
If you have a lot of weight to lose, scale weight will come down, regardless of all the other factors.
The things is, the weight will come down when it wants to, not when you want it to.
The reason I recommend you still use scales is because; people that weigh themselves regularly, manage their weight better than those that don’t. (22)
Instead of weighing once per week, do it everyday, in the morning, naked after the toilet. Then take a weekly average. This will be far more effective than weighing once per week, fully clothed.
These metrics alone are tools and don’t tell the whole story alone, but together they paint a bigger picture. In the same way, you could create a beautiful picture with a pencil alone. However if you combine it with crayons and other stationery, you can create something better.
But if you’re adamant you don’t want to use scales, thats fine too. Just use the other metrics mentioned above.
I get asked a lot what’s the quickest way to lose weight. Technically, the answer would be to cut your arms and legs off.
But I’m sure what you meant was the most efficient way to lose non essential body-fat. That always comes down to the boring basics.
Calorie deficit, resistance training and adequate protein.
Losing scale weight can be water loss, less food volume, glycogen loss, muscle loss or an arm chopped off.
Unless you’re a competitive athlete, I don’t think this is what you’re after.
Body weight and body fat are two different things. You’re looking to lose body fat. Think less about weight and more about fat.
If you got any questions, don’t hesitate to ask.
Josh is a Registered Associate Nutritionist, with the Association for Nutrition (AFN). He completed his degree in Nutrition at the University of Roehampton in 2021. He passed with a First Class with Honours.
Josh is also a tutor for up-and-coming Personal Trainers, where he teaches a Level 4 Advanced Nutrition course. This is for Personal Trainers looking to upskill their nutrition knowledge. This is done at Norfolk Health & Fitness.