weight loss

Why is the United States So Fat and What to do About It

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.

AgeHealthy Body Fat % (Women)Healthy Body Fat % (Men)
20-3921%-32%8%-19%
40-5923%-33%11%-21%
60-7924%-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.

How to Lose Weight and Keep it Off

First lets talk about who needs to lose weight and why.  Weight of course varies with height but what we are really interested in is  what percentage of your body is fat.  This is not quite as straightforward as it sounds.  The only accurate way to measure per cent body fat is to weigh you and then dunk you in a tank of water to see how much water you displace.  This is obviously not a practical way follow your fat percentage, so we use several methods to approximate the percentage of body fat.

The most common (and easiest) method to estimate body fat percentage is called body mass index or BMI and is measured in kilograms per square meter.  This method works fairly well for most people, but it overestimates body fat percentage for some people, especially men,  with large amounts of muscle mass. Normal BMI is between 18 and 25.  Here is a calculator to compute your own BMI.

Another way to estimate the percentage of body fat is to use special calipers to measure the thickness of skin folds on standardized places on your body.  This can be very accurate, but takes a lot of practice to do correctly, so is not very practical for most people to use.  Body fat percentage should be less than 20% for men and less than 30% for women.

The third method is called bioelectrical impedance.  A tiny electric current is passed through your body and the resistance to current flow is measured. Because water passes more current than fat, higher resistance means more fat.  This is probably the least accurate measure because it is also affected by your state of hydration, but followed over time it can be useful.  The most common consumer device that uses this method is the Tanita scale. There are several models to choose from depending on your budget.

If your BMI is less than 40 or your percent body fat is 40% or less for women and 30% or less for men, all you need to do is follow the seven secrets to a long and happy life and not worry about your weight.  If you are beyond those limits, then your weight may be detrimental to your health and it makes sense to try to lose weight.

If you do have a weight problem, no doubt you have read many diet books and tried just as many diets. The good news is that almost all of them work as advertised. The bad news is that within a year, usually less, all the weight comes back and more. Why does this happen?

It turns out that recent research has an answer. When you have been at a certain weight for a long time (we don’t know exactly how long that is) your body takes that weight as a set point and just like a thermostat, your body tries to keep you at that weight.

When you go on a diet and lose weight, your body goes into action to try to get you back up to your set point weight. For one thing, your muscles get more efficient so that you burn fewer calories with the same amount of exercise. Also, there is a hormone called leptin that lets you know when you have had enough to eat at a meal. When you lose weight, leptin levels go down so that it takes larger amounts of food for you to feel full. There are other complex changes in your body chemistry, all designed to get you back up to your set point weight.

So low long do you have to stay at a lower weight to have it as a new set point? We don’t know for sure, but at least a year and perhaps longer.

Pretty depressing, isn’t it?

The only way to beat this system is to make permanent changes in your eating and exercise habits. That rules out all the diet books, because none of those diets are sustainable for the rest of your life. In order to make permanent changes you have to choose carefully. You are more likely to stick to small changes than big ones.

For example if you happen to love ice cream you are probably not going to stick to a change of no more ice cream ever. Maybe you could permanently manage having ice cream only once a week, however. One way to decide what to change is to keep an eating diary for a week and then use the diary to decide one change you think you could live with forever. Once you are successful with that you can keep the eating diary for another week and decide on another small change.

Sometimes very simple things can work. For example one way to automatically reduce portion sizes is to eat off a salad plate rather than a dinner plate. Research has shown this has a subconscious psychological effect. A smaller amount of food looks like more on a small plate. This and other findings about how the presentation of food affects the amount we eat is described in an excellent book by Brian Wasink called Mindless Eating.

What about exercise? You are not likely to lose weight through exercise alone without making changes in your eating habits unless you are doing vigorous exercise for hours a day. That’s just not practical for most folks. Moderate exercise is good for you in other ways though and makes you feel better, which indirectly may help you change your eating habits.

Eventually as you make small permanent changes In your eating and exercise habits you will start to lose weight. It won’t be fast but it’s likely to stay off, and it’s the only way to beat the thermostat system.  A realistic weight loss goal is 10% of your body weight over 6 months to one year.  If you achieve that and sustain it, then you can set a goal for another 10%.

In my experience there are a few people who follow all these rules and still do not lose weight.  Although that is discouraging, following the seven secrets to a long and happy life will still serve to improve your wellbeing and decrease your risk of health problems related to your weight.