Weight loss explained: Why understanding body composition matters more than the scale

With New Year’s resolutions in full swing and gyms filling up, many people are chasing weight loss without fully understanding how their bodies work. According to biokineticist Winile Mothsoane, sustainable weight loss starts with assessment, not guesswork.

Biokinetics is a regulated health profession that uses scientifically prescribed exercise to treat and prevent health conditions. Rather than following generic workouts or influencer routines, biokineticists assess how a person moves, their injury history, muscle balance, and body composition before designing a programme.

BMI vs body fat: why the scale can mislead you

One of the biggest misconceptions around weight loss is relying on Body Mass Index (BMI) alone. BMI only considers height and weight, not what that weight is made up of.

“You can be overweight but not over-fat, or underweight and still carry excess fat,” Mothsoane explains. That’s why body composition matters more than the number on the scale.

Fat mass, muscle mass and bone density all play a role in health and performance

How fat gain actually happens

Everyone is born with fat cells, known as adipocytes. These cells are essential for insulation and organ protection, but problems arise when calorie intake consistently exceeds energy use.

When excess calories are stored, fat cells grow. Once they reach capacity, the body creates new fat cells. Over time, this leads to increasing fat mass and higher health risks such as high blood pressure and cholesterol.

Weight loss, in simple terms, requires creating a calorie imbalance — burning more energy than you consume — but the body resists this change.

Why weight loss feels harder over time

As people lose weight, the brain perceives the energy deficit as a threat and responds by increasing appetite. This is why hunger often spikes when you start exercising or cutting calories.

Consistency is key. Over time, the brain adapts and stops treating weight loss as an emergency.

Short-term fixes rarely workbecause they don’t allow this adaptation to happen.

There’s no single formula that works for everyone

Skipping meals, fasting, or training on an empty stomach may work for some, but not for all. Genetics, hormones, age, stress levels, and lifestyle all affect metabolism.

Mothsoane warns against copying extreme diets or quick-fix trends found online. In some cases, people lose weight rapidly but also lose muscle mass, which weakens the body and slows metabolism.

Why resistance training is non-negotiable

As we age, muscle mass is easier to lose and harder to regain. Resistance training — using weights, bands, or bodyweight — helps preserve muscle, protect joints, and support long-term weight loss.

“Losing weight without protecting muscle is a mistake,” Mothsoane says. Strong muscles improve mobility, posture, and everyday function, not just appearance.

Movement, posture, and injury prevention

Modern lifestyles involve long hours of sitting, which shortensmuscles and reduces joint mobility over time. This leads to poor posture, limited movement, and higher injury risk.

Regular movement, stretching and strength training help maintain flexibility and joint health. Many injuries, especially in runners, stem from weak core muscles and poor movement patterns rather than the activity itself.

Can you exercise too much?

Yes. Overtraining without proper recovery keeps the body in a constant state of inflammation. Recovery days, adequate sleep, hydration, and nutrition are essential parts of any effective weight loss programme.

Progress happens during recovery, not just during workouts.

When to seek professional help

If you’re unsure where to start, struggling with injuries, or not seeing results despite effort, a professional assessment can make a difference. Biokineticists often work alongside physiotherapists and chiropractors, focusing on the final stages of rehabilitation and long-term injury prevention.

Mothsoane practises at Virgin Active, where biokineticists are available at many clubs to help members understand their bodies and train safely.

The bottom line

Weight loss isn’t about punishment, starvation, or shortcuts. It’s about understanding your body, building muscle, moving well, and staying consistent. When exercise is matched to your body’s needs, results are safer, healthier, and far more sustainable.

For more information, listen to Mothsoane using the audio player below: