We often judge our fitness, progress in dieting, and unfortunately, sometimes our self-esteem based on what appears on the scale when we step on it.
While the bathroom scale can be a useful tool for detecting obesity or tracking weight loss progress, it can be misleading for many of us. This includes athletes with higher-than-average weight and those with a “skinny fat” body type, especially if it reassures them that they have a healthy weight.
To understand the issue with the “skinny fat” phenomenon, we need to clarify three concepts:
- What is BMI?
- What is body composition?
- What is a “skinny fat” body type?
A Few Words About BMI
BMI (Body Mass Index) is a statistical measure that assesses an individual’s body weight relative to their height. It is calculated by dividing the weight in kilograms by the square of the height in meters. BMI = weight (kg) / height² (m²) BMI is widely used to determine healthy weight, overweight, or underweight. The method was developed by a Belgian polymath, Adolphe Quetelet, between 1830 and 1850.
However, BMI does not consider the quality of the components that make up body weight or body composition. Since fat, muscle, and bone have different densities, a person with a thin bone structure and less muscle may carry much more fat than someone with the same BMI but a more muscular, strong-boned physique. Therefore, BMI can misleadingly indicate overweight in bodybuilders and other muscular individuals.
What is Body Composition?
Body composition refers to the ratio of lean body mass (water, bone, organs, and muscle tissue) to fat tissue (fat mass). With the advent of bioelectrical impedance analysis (e.g., InBody™) and dual-energy X-ray absorptiometry (DEXA), we get a better and more complete picture of our body composition. Depending on the type, body composition measuring devices can provide more than 40 data points, offering a much fuller picture than BMI.
What is a “Skinny Fat” Body Type?
The term “skinny fat” describes a body type where an individual appears thin or has a normal weight based on BMI but has a high body fat percentage and low muscle mass. This body composition can result in a person not looking overweight externally but facing the same health risks—such as insulin resistance, high blood pressure, or heart disease—as someone considered overweight based on BMI.
In older adults, this condition is often referred to as sarcopenic obesity, as it is associated with a significant reduction in skeletal muscle (and bone mass), often leading to orthopedic injuries, inability to maintain independence, and general weakness.
What Causes Someone to be “Skinny Fat”? Like most things, both genetics and lifestyle play a role. Some individuals are genetically predisposed to this condition, tending to store more visceral fat (abdominal fat) and less subcutaneous fat (under the skin) than their normal-weight, metabolically healthy peers. In these cases, these individuals can reach unhealthy levels of body fat before their BMI indicates they are overweight.
However, genetics are not entirely to blame. The same lifestyle choices that lead to obesity can lead to normal weight obesity. This includes, but is not limited to, poor dietary choices (higher fat and carbohydrate intake than ideal, with low protein intake), poor sleep, high stress, and lack of exercise. When examining the causes of normal weight obesity, it is important to highlight the role of lack of exercise, particularly resistance training (e.g., weight training), as low skeletal muscle mass plays a significant role in developing a “skinny fat” body type.
How to Manage Normal Weight Obesity? Managing normal weight obesity is more complex than simply advising the client or patient to lose weight, exercise more, and eat less. For a “skinny fat” individual, the problem is not their weight but their body composition. Advising them to lose weight often results in muscle loss and worsening of the “skinny fat” body type.
What is the Best Way to Manage Normal Weight Obesity?
- Exercise: The type of exercise matters. Cardiovascular exercises like walking, cycling, dancing, running, and swimming can be beneficial for increasing daily energy expenditure, improving cardiovascular and respiratory health, and reducing fat mass. However, they should not be the sole focus, as muscle mass needs to be increased, which can be achieved through resistance training (weight training).
- Diet: Optimal nutrition is crucial for a “skinny fat” body type. A significant calorie deficit is not the solution, as it leads to a reduction in lean body mass, which we want to avoid. If fat loss is needed, a small calorie deficit combined with high protein intake can help maintain optimal body composition. A daily intake of 1.2-1.5 g of protein per kilogram of body weight (preferably from plant-based sources) promotes lean body mass growth and fat mass reduction.
Similarly, a moderate-fat and modified-carbohydrate diet, reducing refined sugar intake, and ensuring adequate fiber intake (25-30g/day) can also help achieve a more favorable body composition.
- Stress Management: Learning effective stress management techniques and establishing proper sleep habits contribute to managing normal weight obesity.
When we look at it, the “recipe” components are the same as for obesity, but the quality and quantity of the ingredients matter.
If you lead a relatively sedentary lifestyle, it might be a good idea to undergo a body composition analysis rather than relying solely on BMI to determine if you are at risk for normal weight obesity.
Source: https://blog.nasm.org/skinny-fat
Nicole Golden: Normal Weight Obesity: How to Manage a ‘Skinny Fat’ Body Composition
