The surprising link between neck thickness and health

When fitness experts try to assess a person's health, they usually perform a series of standard measurements. First they measure a human's height, then compare that with the circumference of their chest, waist, hips and/or thighs. The goal is to help each individual achieve a thickness that suggests the healthiest percentage of body fat — not so low as to be malnourished, nor so high as to put a person at risk of cardiovascular diseases.

Yet there is one other part of the body experts say you should also measure to learn your health, although it often does not receive enough attention: Your neck

"Upper‐body subcutaneous fat is a unique fat deposit, and its measurement can be approximated using neck circumference," said a 2022 study in the Journal of the American Heart Association, one that measured different types of subcutaneous fat (meaning under the skin) and found a link between neck thickness and heart disease. "Neck circumference has been shown to be associated with increased cardiovascular risk. There is evidence that free fatty acid release from upper‐body subcutaneous fat is higher compared with lower‐body subcutaneous fat." Free fatty acids are also associated with diseases like cancer and type 2 diabetes.

The authors of that study found, much to their fascination, that the more than 500 examined patients were much more likely to develop incident atrial fibrillation (an irregular and often very rapid heart rhythm) if they had thick necks than if they did not. Other scientists who study human health have, for their own reasons, also concluded that neck fat is an important and under-appreciated indicator of overall health.

"Traditional measures of obesity include the body mass index (BMI) and waist circumference – factors with a bearing on cardiometabolic disease," Dr. María José Arias Téllez, a postdoctoral researcher at the University of Chile's Department of Nutrition, told Salon. "Several studies have proposed that fat accumulation in the neck (measured as neck circumference [NC]) provides an indicator of upper body fatness, being NC associated with obesity and cardiovascular risk independent of BMI" and a person's belly fat (visceral adipose tissue).

While the fat which accumulates around a human's abdomen accounts for only a small percentage of the total systemic free fatty acid that is released into the body, upper body fat contributes more than half, "rendering it the largest contributor of all," Téllez said. This means that this type of upper body fat "and particularly the neck adipose tissue, might, at least partially, explain the obesity-related cardiometabolic risk not covered by the [visceral adipose tissue]."

Téllez concluded, "In the last time, neck circumference has been associated with cardiometabolic risk factors as well as type 2 diabetes, insulin resistance and obstructive sleep apnea syndrome [in which a person's excess fat compresses their windpipe while they sleep], arterial hypertension in children, adolescents and adults."

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Dr. Francisco M. Acosta, an expert in biomedicine at the University of Turku who specializes in the role of brown fat on human biology, clarified exactly why neck fat seems to be overlooked in how it is so uniquely linked to ill health.

"Our knowledge about how neck adiposity relates to health issues has remained obscured – in the shadow of visceral adipose tissue harmful effects – for a long time," Acosta said. "However, nowadays we know that there is a clear relationship between neck thickness/adiposity with cardiometabolic risk and inflammation, from younger to older populations. Indeed, data from large cohort studies show that neck thickness correlates insulin resistance and diabetes, metabolic syndrome components, fatty liver disease, subclinical atherosclerosis — and even with a higher rate of cardiovascular events, mortality and all-cause mortality."

Acosta's views were echoed by Dr. Sarah Preis, an associate professor in biostatistics at Boston University's School of Public Health.

"Higher neck circumference is correlated with the presence of many adverse health conditions, even after accounting for traditional adiposity measurements, such as BMI," Preis said. "These conditions include sleep apnea, metabolic risk factors (insulin resistance, diabetes, high blood pressure), cardiovascular disease and atrial fibrillation. To date, cut points to define 'high' versus 'low' neck circumference have not been established in the general population. Individual research studies have defined cut points for neck circumference that are specific to the age and sex distribution of the participants in their study sample, however, it would not be appropriate to use these values for the average person."

Unlike Preis, however, Acosta does offer a rule-of-thumb that ordinary people can use to measure their own necks.

"The best way to accurately assess neck circumference is to measure it using an inextensible metallic tape over the thyroid cartilage, perpendicular to the longitudinal axis of the neck," Acosta said. "During this measurement subjects were in an anatomical position, standing or sitting with the head in the Frankfort plane [straight forward] and the shoulders relaxed. Although neck circumference increases with body mass index, and is normally larger in men than in women, it is a robust measure and it is not so likely to be influenced by the body types, although it has been reported that people with larger visceral adipose tissue depots (more fat in the abdominal area) are also likely to have a larger neck circumference."

Acosta added that men with a neck circumference thicker than 37 centimeters [14.5 inches] and women with a neck circumference thicker than 34 centimeters [13.4 inches] "can be classified as overweight, and those with a neck circumference [greater than] 39.5 [15.5 inches] and 36.5 [14.4 inches] (respectively) can be classified as people with obesity based on a study conducted in a large cohort of Israeli people." Although an individual's height may influence these parameters to an extent, "this is not yet an extended marker in the field," meaning it is not yet well-studied.

If one finds that their neck is too thick to be healthy, they should focus on improving their lifestyle so that the conditions linked to thick necks, as well as diseases like hypertension, cannot begin to gain a foothold in a person's life. Even though the causal link between neck circumference and adverse health outcomes is unclear, Preis said that it is significant to note how "neck circumference is a proxy measure of upper body subcutaneous fat, a distinct fat depot that is a major source of circulating free fatty acids in the body. Increased levels of free fatty acids are associated with insulin resistance and dyslipidemia," or elevated cholesterol levels that can lead to atherosclerosis.

Téllez confirmed this, noting that "upper body fat is a major contributor to systemic free fatty acids." Like Preis, Téllez argues that "one could hypothesize that neck adipose tissue, an upper body fat depot, is an important contributor to systemic free fatty acids and the development of cardiovascular diseases.

Despite the relevance of one's neck thickness to one's health, Preis acknowledges that most doctors still do not measure one's neck as a matter of habit.

"Currently, neck circumference is not used in routine clinical practice," Press said. "However, since high neck circumference is correlated with increased body mass index, it would be reasonable for a person who is concerned about the thickness of their neck to consult with their primary care physician."