Dietetics

How BIA helps distinguish between fat loss and muscle loss in older adults

Unintentional loss of muscle mass and strength occurs relatively frequently in older adults. At the same time, fat mass may either increase or decrease. Both changes can negatively affect health, making it important to distinguish between muscle loss and fat loss. Bioelectrical impedance analysis (BIA) can be used for this purpose.

Unwanted Muscle Loss Is a Problem in Older Adults

Due to natural ageing, body composition changes (Palmer & Jensen, 2022). This often occurs without being directly visible in body weight. Unintentional loss of muscle mass and strength is relatively common among older adults. Natural ageing contributes to this, but inadequate nutrition (insufficient energy and protein intake), physical inactivity, and disease can exacerbate the problem (Larsson et al., 2019).

Below certain threshold values, the condition

Insights into Long-Term Results: The Benefits of Regular BIA Measurements

A scale makes it easy to determine a client’s body weight. However, this provides limited information. BIA measurements (depending on the model) can also provide data on body fat percentage, visceral fat mass, muscle mass, body water, and phase angle. By monitoring this information regularly, it becomes possible to work more purposefully toward an individual’s health and fitness goals.

Weight Alone Says Very Little

Using a simple scale, only body weight can be measured. From this, the Body Mass Index (BMI) can easily be calculated. BMI is the most commonly used measure to express obesity (Heymsfield et al., 2025).

BMI is calculated by dividing body weight by height squared. A BMI of 18.5–25.0 kg/m² is considered normal. A BMI between 25.0 and 30.0 kg/m² indicates overweight, and values above this indicate obesity.

A limitation of BMI

Attention to Muscle Mass Loss in Malnutrition

Malnutrition is an underestimated problem. It is common and has adverse consequences for health. A significant proportion of these consequences result from the loss of muscle mass. It is therefore advisable to measure muscle mass in cases of (suspected) malnutrition. This can support both diagnosis and monitoring of treatment effectiveness.

What Is Malnutrition?

Various definitions of malnutrition are in use. Internationally, the term malnutrition is preferred over undernutrition. The World Health Organization (WHO) applies a broad and general definition, whereas the European Society for Clinical Nutrition and Metabolism (ESPEN) uses a more clinical definition. In the Netherlands, the ESPEN definition is generally followed.

WHO Guidelines

The WHO definition is broad and intended for public health contexts. Malnutrition refers to deficiencies, excesses, or imbalances

What Do the Different BIA Results Mean?

Most people have a clear idea of what body weight represents. Modern BIA equipment goes further and displays a range of results. These data can be useful, but what exactly do they mean?

Classification of Body Composition

Body weight can be classified at different levels:

• Atomic level (carbon, oxygen, nitrogen, etc.)

• Molecular level (fat, protein, water, etc.)

• Cellular level (intra- and extracellular cell mass)

• Functional level (adipose tissue, skeletal muscle, bone tissue, etc.)

• Anatomical level (trunk, arms, legs, etc.)

The most commonly used classification is the molecular level, which can be subdivided into multiple compartments (see Figure 1). The most widely used models are based on two, three, or four compartments (Prado et al., 2025). These compartments can be estimated using bioelectrical impedance analysis (BIA).

Figure 1: Overview of the multi-component model

The Evolution of Body Composition Measurement: From BMI to BIA

Measuring body composition is essential for understanding health status, nutritional status, and the risk of chronic diseases. Over the years, various methods have been developed, ranging from simple anthropometric techniques to advanced technologies that provide detailed information on fat mass, fat-free mass, and body water.

Importance of Body Composition

Assessing body composition provides important insights into nutritional status and can be used as an indicator of overall health (Holmes & Racette, 2021; Jo et al., 2025). Moreover, it enables healthcare professionals to develop personalized health strategies and to monitor responses to interventions.

History of Body Composition Measurement

Today, numerous techniques exist to measure or estimate body composition with varying degrees of accuracy. However, this was not always the case. The need

Exercise Interventions to Improve Body Composition

Exercise interventions aimed at improving body composition focus on increasing muscle mass, reducing fat mass, improving fat distribution, and stimulating bone density. This approach not only helps improve overall health but also contributes to promoting a vital and active life.

Increasing Muscle Mass

To build muscle mass, or to limit its loss, it is necessary to progressively load the muscles and allow sufficient rest for recovery. This stimulates muscle protein synthesis and ensures a positive balance between muscle breakdown and muscle growth (Booth et al., 1991). Resistance training is particularly suitable for this purpose, including in individuals with obesity when combined with an energy-restricted diet (Lopez et al., 2022; Binmahfoz et al., 2025).

Resistance may consist of:

• Free weights: barbells, dumbbells, kettlebells

• Machines: strength equipment

How much protein do you need when training for more muscle mass?

Does your client engage in strength training and want to build more muscle mass? Then sufficient protein intake plays a crucial role. Discover below approximately how much protein your client needs and how you can obtain it from the daily diet (or possibly with a protein supplement).

Importance of muscle mass

Skeletal muscles make up the largest part of fat-free mass (approx. 40–60%). Besides enabling movement, muscle mass is also important for good health. Reduced skeletal muscle mass and muscle function in adults is, for example, associated with chronic diseases, a lower quality of life, sarcopenia, and physical limitations (Wolf et al., 2006; Ebner et al., 2015; Larsson et al., 2019).

Why is fat loss more important than weight loss in obesity?

Many people with obesity focus on lowering their body weight when they want to lose weight. But it is actually fat mass that they want to lose. Fat loss provides greater health benefits than weight loss alone, because it targets the reduction of the harmful effects of excess body fat, especially around the abdominal organs. In addition to monitoring body weight, it is therefore also advisable to look at fat loss.

Which BIA monitor is the most suitable for me as a dietitian?

A body analysis measurement is a fixed part of my consultation. It gives me a lot of information about body composition, which guides good dietary advice. Weight alone says too little. A BIA measurement also provides insight into fat percentage, muscle mass, fluid percentage and visceral fat.

When purchasing a BIA monitor I pay attention to the following factors:

1. Ease of use

Simple to operate and easy to store in a lockable cabinet.

2. Service 

Check the warranty period and whether the supplier provides service after purchase. My experience is that a BIA monitor lasts at least 10 years. I even have one that has been going for 15 years. It works like a charm, but this is also because the supplier TANITA quickly solves my problems, for example if there is a technical problem and the BIA monitor does not want to start up.