I’m going to take a break from the series of posts on healing relationships for a while and start a new series of posts about the epidemic of fatness in the U.S. This is an especially opportune time to talk about the epidemic of overfatness in the U.S.. Many people have gained fat during the last few years of the pandemic, and the holidays always make it worse. In this series I will talk about the causes of the epidemic, how to measure body fat, some common myths about fat loss and then discuss the science behind fat loss and fat gain. Finally I will give some practical suggestions for losing fat and keeping it off.

The epidemic of fatness

I use the term fatness on purpose, rather than overweight or obesity. It is really too much fat that causes bad health consequences. The CDC defines obesity as a BMI (body mass index) of 30 or higher. I will talk later about the problems of using BMI as a measure of fatness, but when the BMI is 30 or higher it is a pretty good indicator of fatness and health risks. In 2018 (the last year we have complete data) 42.4% of adults in the U.S. had a BMI of 30 or greater. That means nearly half of adults have all the health risks associated with overfatness! These include heart disease, stroke, cancer and diabetes. More than 10% of adults have type 2 diabetes. In the 1950’s only 10% of adults in the U.S. had a BMI of 30 or greater and less than 1% had type 2 diabetes. We see the same trends in children and adolescents. What happened?

In 1980 there was a scientific consensus that dietary saturated fat caused heart disease. The evidence was flawed, but that will be a subject for another post. The US dietary guidelines for that year recommended lowering dietary fat to 30% of calories. People reduced their fat intake modestly, but the food industry substituted sugars for fats in processed foods. This increased total calorie intake. There were other factors as well. The average restaurant meal is four times larger than it was in the 1950’s. The size of American manufactured dinner plates increased from 9.6 inches to 11.8 inches. Average physical activity for both adults and children has decreased as well. The result of all of these factors has resulted in a 24% increase in average daily calorie intake.

Type 2 diabetes is caused not by insufficient insulin, but by resistance to the insulin your body makes. The most common cause of insulin resistance is being too fat. Thus the epidemic of diabetes parallels the epidemic of fatness.

Are you too fat?

The most common measure of how fat you are is called BMI (body mass index). The BMI is your weight in kilograms divided by your height in meters squared. The easiest way to calculate your BMI is to use a BMI calculator app that lets you enter your height in inches or feet and your weight in pounds. Here is a link to one BMI calculator.

Although BMI is easy to calculate it is not a very good measure of body fat. It is most useful at the extremes. If your BMI is over 30 then there is a 95% chance that you have an unhealthy amount of fat. If your BMI is less than 18 then your body fat percentage is likely to be too low to be healthy. In between these extremes, BMI is not very good as an estimate of unhealthy body fat. For people who have a high amount of muscle mass (professional athletes for example) BMI can significantly overestimate body fat. For others, particularly the elderly, BMI significantly underestimates per cent body fat.

Other ways to estimate body fat

Ideal body percent body fat varies by sex and age. Below is a table of ideal body fat percentage from Beth Israel Lahey Health Winchester Hospital.

Age	Healthy Body Fat % (Women)	Healthy Body Fat % (Men)
20-39	21%-32%	8%-19%
40-59	23%-33%	11%-21%
60-79	24%-35%	13%-24%

Electrical impedance

There are a number of consumer grade scales that advertise that they measure weight and per cent body fat. They use something called electrical impedance to do this. A small imperceptible electric current is passed through your body. Fat and bone have more resistance than muscle and body water. The machine uses a formula to calculate per cent body fat. The formula uses age, sex and height. These values are usually entered through some sort of smart phone app.

Most of these scales use only two electrodes, one for each foot. These are not very accurate. Scales that use four electrodes, one for each foot and one for each hand, are considerably more accurate. Most of the four electrode models cost thousands of dollars, but I did find one that sells for $349. Here is a link to that scale’s website.

Skin fold calipers

Measurement of per cent body fat using skin fold measurements is quite an accurate way to measure body fat. Skin fold calipers are not particularly expensive but it takes a lot of experience to use them correctly. The skin folds have to be measured in seven different places. Some trainers at gyms have been trained to do skin fold measurements. This is not a practical method to use at home.

Other methods for measuring body fat

There are some very accurate ways to measure body fat including a special kind of x-ray and being immersed in a tank of water to see how much water you displace. Both of these methods require expensive specialized equipment. These methods are mostly used in research and are not even available at most hospitals.

Waist circumference

The biggest health risk is the amount of fat inside the abdomen around the intestines and organs. This is called visceral body fat and it is easy to measure. Get a cloth tape measure and measure your waist circumference. The correct way to do this is to feel for the top of the pelvic bone on both sides and measure just above this. That will be about at the level of your belly button. For women if your waist circumference is greater than 35 inches you have triple the risk of diabetes, heart disease and cancer. Women with a waist circumference of 31.5 inches to 35 inches have a lower risk, but still moderately elevated. Women who have a waist circumference of less than 31.5 inches have the lowest risk. For men the equivalent numbers are: High risk: greater than 40.2 inches. Moderate risk: 37 to 40 inches. Low risk: less than 37 inches.

Fat around the hips and buttocks is not associated with any significant health risk. In other words, pear shaped is better than apple shaped!

Losing Fat

Lets say you have calculated your BMI, measured your waist circumference and perhaps measured your body fat percentage using one of the impedance devices. You have determined that you have an unhealthy amount of body fat. The next post will discuss myths about fat loss strategies as well as what we know about the science of fat loss and fat gain. For those of you who want to get a little preview, you can review the brief post I did in 2015 called How to Lose Weight and Keep It Off.