Body Fat

In the US, 91% of adults and 69% of children are estimated to be overfat.

The Prevalence of Overfat Adults and Children in the US

I saw this statistic and many follow-up questions popped up:

  • what is “overfat?”
  • why is being “overfat” bad?
  • what body fat is % “too much fat?”
  • how can one measure “body fat % accurately?”

So I dove in to the aforementioned paper and have answered these questions in Q&A form below.

What does it mean to be “overfat”?

The overfat condition is defined as excess body fat sufficient to impair health.

How does excess body fat “impair health”?

Excess body fat is associated with poor health, and the development of insulin resistance and low-grade systemic chronic inflammation. These conditions can lead to various cardiovascular and metabolic (cardiometabolic) impairments such as dyslipidemia, increased blood glucose, and hypertension, raising the risks of chronic diseases such as Type 2 diabetes, cardiovascular diseases, and most cancers. Chronic inflammation has also been linked to neurodegenerative diseases, including the most common cause of dementia, Alzheimer’s disease.

Physical performance impairments associated with excess adiposity include musculoskeletal disorders, such as lower-back and other pain syndromes, reduced work productivity in forms such as absenteeism and disability, as well as lower quality of life, and include locomotive disorders such as knee and hip osteoarthritis, lumbar spondylosis, and osteoporosis. Performance was also assessed in normal-weight obese children aged 3–6 years, who showed significantly worse levels of fundamental motor skills compared to their normal-weight non-obese counterparts. As fundamental motor skills in early life play a crucial role in physical, cognitive, and social development, childhood adiposity may indirectly exacerbate physical performance impairments into adulthood.

How much body fat is “excess body fat”?

While there is no consensus on how to define excess body fat percentage, Lohman’s criteria of suggested cutoffs is widely accepted in body composition research:

  • >17.6% for males
  • >31.6% for females

However, measurable health impairments associated with ≥2 cardiometabolic abnormalities were found at DXA-derived body fat levels of:

  • >15.3% in men
  • >29.8% in women

How can one measure their body fat %?

Various research methods have been used to quantify body fat levels in humans, including bioelectrical impedance and hydrostatic plethysmography, with DXA (Dual-energy X-ray Absorptiometry) being one of the most accurate and precise methods currently accessible.

[Note: an affordable way to get a DXA scan for only $45 is through BodySpec]

What about BMI?

BMI (Body Mass Index) is a weight-to-height ratio, calculated by dividing one’s weight in kilograms by the square of one’s height in meters and used as an indicator of obesity and underweight.

Determination of overweight and obese classifications are usually based on measures of body mass index (BMI), with overweight defined with a score of ≥25 to <30 kg/m2 and obesity as ≥30 kg/m2. However, while BMI can overestimate fat mass in certain populations, including Polynesians, African American, and elite strength athletes, because BMI is not a direct measure of body fat it can misclassify up to 50% or more patients with both increased body fat and its associated disease risk factors

How else can one measure body fat %?

Abdominal fat distribution, assessed through waist circumference, waist-to-hip ratio and waist-to-height ratio measurements, can be useful in the clinical assessment of adiposity-related risk, although, like BMI, these measures do not accurately estimate body fat percentage.

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