Most of us use the scales to track progress, but your weight only tells you one thing: how much your total body weighs. It doesn’t tell you what that weight is made up of.
You may be losing fat, gaining muscle, losing muscle or carrying more visceral fat without seeing a major change on the scales. That’s where a DXA body composition scan can give you a much clearer picture.
In this discussion with registered clinical nutritionist Anastasia Bennett, Bone and Body Blueprint radiographer Heidi Richardson explains what body composition is, how DXA scanning works and why it is more useful than watching weight on the scales.
Body weight vs body composition.
Body weight is simply the number you see when you step on the scales. Two people can weigh exactly the same but have very different body compositions. Your weight can also stay relatively stable while you lose fat and build muscle, which is why the scales don’t always reflect the progress you’re making. Body composition looks at what makes up that weight, including fat, lean mass and bone.
How is DXA different from the body-composition scales at gyms?
Many gym body composition machines use bioelectrical impedance analysis (BIA). They send a small electrical current through parts of the body, then use that measurement to estimate fat and muscle. Because the current may travel mainly through the legs or upper body, results can be influenced by where you carry your fat and muscle.
DXA works differently. It uses low-dose X-ray technology to accurately assess fat, lean tissue and bone throughout the body, providing detailed information about how your weight is distributed.
What does a DXA body composition scan show?
A body composition scan can provide information such as:
Total fat mass.
Lean mass.
Body fat percentage.
Visceral fat.
Muscle and fat distribution.
Fat Mass Index and Lean Mass Index.
Basal Metabolic Rate.
At Bone and Body Blueprint, our qualified radiographers can explain what the measurements mean, so you can use that information or share it with your nutritionist, personal trainer or other health professional.
One of the biggest limitations of the scales is that they can’t tell you whether weight loss is coming from fat or muscle.
Why muscle matters.
One of the biggest limitations of the scales is that they can’t tell you whether weight loss is coming from fat or muscle.
This becomes increasingly important as we age, particularly for women through their 40s, 50s and beyond. Maintaining muscle supports strength, mobility and your skeleton, so losing weight isn’t necessarily the whole goal.
A DXA scan gives you a baseline, and follow-up scans can show whether the changes you are making through nutrition, exercise or lifestyle are helping you lose fat while preserving (or building) muscle.
You can be slim and still have higher visceral fat.
Body composition can also reveal information that isn’t obvious from appearance alone. Visceral fat is the fat stored deeper inside the abdomen around the internal organs. Someone who appears slim can still have higher visceral fat, while someone with a larger body size may have comparatively low levels.
This is another reason why scales don't give you the full picture.
Using DXA as a baseline.
You don’t need to be trying to lose weight to have a body composition scan. Many of our clients simply want a baseline so they can understand where they are now and compare it with future scans.
It can be useful if you are starting a new exercise programme, strength training, changing your nutrition, working towards fat-loss goals, going through perimenopause or menopause, or simply wanting to track your health and fitness over time.
Some clients return annually or every couple of years as a general check-in.
DXA body composition scans in Te Awamutu and Pukekohe.
Bone and Body Blueprint provides DXA body composition scanning at our clinics in Te Awamutu and Pukekohe.
If you want to know more than the number on your bathroom scales, a DXA body composition scan can show you what’s actually changing inside your body.
