weight loss

The Psychology of Eating and How to Use It to Your Advantage

We eat according to internal cues. We eat when we are hungry and stop when we are full. Both of these statements are false! Our bodies are very poor at letting us know how many calories we are eating. External cues in the environment are powerful influencers of what and how much we eat. Study after study shows that many of our eating habits are automatic and influenced by: the size of the plate we use; whether we use a short wide or a tall skinny glass; the size of the package that our food comes in. All of these studies are summarized in a very readable book by Brian Wansink called Mindless Eating. It’s an old book, published in 2006, but human nature and the psychology of eating have not changed since 2006. He is a little easier on the food companies than I would be, but I highly recommend reading it. Here is a list of external cues, validated by research, that cause us all to eat more than we think.

  • Distraction (eating while watching television, reading the newspaper or eating with friends or family)
  • Size of food package (we automatically eat more from a bigger package)
  • Size of plate (we eat less when we eat from a small plate than a large plate)
  • Tall skinny vs short wide glass (a tall skinny glass looks like more liquid than the exact same amount in a short wide glass. We drink more from the short wide glass)
  • Convenience (the more conveniently a food is available, the more we eat)
  • Labels (If foods are labeled low fat, or make health claims we eat more of them)
  • Portion size (we tend to eat everything we are served, regardless of portion size)

The Mindless Margin

Depending on how these external cues are manipulated we generally tend to eat twenty percent more or twenty percent less without even realizing it. Dr. Wansink calls this ”The Mindless Margin.” His research and that of others shows that we can cut our calorie intake twenty percent without triggering all the things that the body does to make us regain the fat we lose. That is somewhat controversial, but we know that modest weight loss can be permanent so lets do the math.

The average American eats about 3600 calories per day. Even eating that many calories, for most people weight stabilizes because we burn more calories to move our large bodies around. If we reduce that average daily calorie intake by twenty percent, that means that we have reduced our average daily calories by 720 calories per day. Over the course of a year we will have reduced our calorie intake by 262,800 calories. That equals a fat loss of 75 pounds!

Big changes vs small changes

Big changes to anything in our lives are much harder to sustain than small changes. Most diet and exercise plans involve big changes to our lifestyle. Those are hard to sustain by themselves and also maximally trigger our bodies to do all the things that eventually make us regain the fat we lost (see my previous post The Biology of Fat Gain and Fat Loss).

Small changes are much easier to stick with. These kinds of changes need to be individualized to our own eating and exercise patterns, but there are a few small changes that work for everyone. If you make three consistent changes that reduces your average calorie intake by only 300 calories a day you will lose 30 pounds in a year. If in addition you increase your exercise by 100 calories a day (walking one mile) you will lose an additional 10 pounds. You will not feel deprived or hungry.

Small changes everyone can make

  • Switch from dinner plates to salad plates. You will automatically eat about 20% fewer calories without even knowing it.
  • Do not eat food out of a box or package or while standing in front of the refrigerator. Always serve whatever you plan to eat on a salad plate or in a small bowl.
  • Do not eat your food while watching television or while reading. If you must eat for a particular TV show, serve your plate before you sit down and don’t go back for seconds.
  • Stay away from the snack food aisle in the grocery store. Willpower does not work. If snacks are easily available, you will eat more calories. If someone else buys snacks, store them in the back of the pantry where it takes more effort to get to them. If you do the shopping, make a list before you go to the grocery store and stick to it.
  • If you drink beverages with calories (soft drinks, fruit juices) Use a tall skinny glass rather than a short fat glass. You will automatically reduce the calorie intake from the beverage by about ten to twenty percent. It is better of course to drink water or other calorie free beverages.
  • Eat slowly. Food should taste great, which means you should enjoy every bite. Do not put another bite in your mouth until you have chewed and swallowed the previous bite.
  • Wait at least twenty minutes after finishing one serving before you have seconds. It takes about twenty minutes for the feeling of satiety (feeling full) after a meal.
  • When you are shopping, park your car as far away as you can from the store. Take at least one flight of stairs rather than take the elevator. Remember that every mile of walking burns about 100 calories. You don’t have to walk the whole mile at one time.

How often should you weigh yourself?

This is pretty much up to you. If you decide to weigh yourself daily, make sure to do it at the same time every day. The morning is best. Weigh yourself without clothes just before or after your shower. Remember that your body is 60 percent water so that your state of hydration and how much water you retain (say from eating something salty the night before) will cause your daily weight to vary as much as two or three pounds. If you weigh yourself daily you should keep a record of your average daily weight for each week. That will be a much better measure of fat loss or gain.

You could also weigh yourself once a week or even once a month. You could decide not to weigh yourself at all, but then you won’t know if the habit changes you have made are enough to produce fat loss. I recommend weighing yourself at least once a month.

Good Nutrition

If you make the small changes I have suggested (or others that are individualized for you) you will lose fat slowly without changing the foods you eat and like. If you want to eat healthier as well as lose fat then check out my next post.

The Biology of Fat Gain and Fat Loss

Fat storage is a way for mammals to manage energy allocation. Fat cells are not simple storage depots, but are metabolically very active. They respond to and produce hormones and other messenger molecules. A certain amount of body fat is essential for mammals, especially humans who have to maintain a large brain which uses a lot of energy. In adult humans 20% of basal metabolism is devoted to maintaining the brain. For infants, that number is closer to 80%. Fat storage gives humans the flexibility to manage environmental stresses such as variation in food supply.

In most of human history there was a balance between energy intake (eating) and energy output. Energy output includes energy to keep the body intact (basal metabolism), energy required to digest food (thermic effect of food) and exercise. Some of the energy from eating goes into fat storage, but the quantity of body fat is also kept in balance. This balance of energy intake, fat storage, and energy output is maintained by a complex feedback system. Most of the research into how energy balance happens has been done in animals, and we still don’t understand exactly how that translates to humans, but we are able to sketch the broad outlines of how the system works. This system involves messenger chemicals and the reward system in the brain. I won’t go into all the complexities here (It is so complicated it would make your eyes cross) but I will give you the simple version.

Leptin

Fat cells produce a hormone called leptin. The amount of leptin they produce is proportional to the amount of fat storage. Leptin decreases appetite and increases satiety (feeling that we have had enough to eat).

Ghrelin
When the energy output is greater than the energy input fat storage decreases and leptin decreases. The stomach makes a hormone called Ghrelin, which increases appetite. We then eat more food until the body fat gets back to the balance point.

The brain reward system

Humans evolved to find sweet high calorie density foods intensely pleasurable. That is probably because such foods were rare or at least seasonal for our hunter-gatherer ancestors. These kinds of foods cause dopamine release in the brain. This is the same system that makes drugs of abuse pleasurable. Eating in general stimulates this system to some extent. From an evolutionary standpoint eating being pleasurable has obvious survival benefit.

How fat storage gets out of balance

Our hunter gatherer ancestors took in lots of calories, but they also burned lots of calories in the hunting and gathering part. In our modern society we don’t have to exercise very much to get our food, so our daily calorie expenditure is a lot less on average than our hunter gatherer ancestors. Moreover, we have the big food industry which has learned very well about the kinds of foods that stimulate our brain reward system the most. The more calories we eat, the bigger their profits. The foods that maximize their profits are calorie dense processed foods with lots of sugar and starchy carbohydrates. We live in what the scientists call an “obeseogenic” environment. The easy (and cheap) availability of high sugar, high carbohydrate foods maximally stimulate the brain reward centers and overwhelm the rest of the energy and fat regulatory system. The result is that many of us increase fat storage up to the point that the extra calories it takes to move our large bodies around get most of us into balance again, but at a much higher level of body fat. Some unfortunate people continue to gain fat until they become disabled by the huge amount of body fat they carry. As I discussed in the previous post, that increased percentage of body fat increases the risks for heart disease, diabetes and cancer.

Addressing the epidemic of overfatness

While I intend to focus later on what individuals can do to lose fat permanently the thing that all of us need to do is to work at a political and social level to change the ”obeseogenic” environment. That will include things that increase the expense of high sugar high carbohydrate foods (like voting for taxes on sweetened beverages) and decrease the expense of healthy unprocessed foods like fresh fruits and fresh vegetables (like allowing food stamps to be used at farmers markets). It is unconscionable that ”food deserts” exist in some communities so that the only foods available are at convenience stores that sell only obeseogenic foods. We also need to work toward changing the exercise environment so that all communities (not just the wealthy ones) have safe walking trails and exercise facilities. All of us, fat or thin, need to do what we can to change the food and exercise environment.

The biology of fat loss

The only way to lose fat is for the calories we eat to be less than the calories we burn. That is a truism, but it is not very helpful in creating strategies for successful fat loss. So what does the body do when we change our energy balance to less energy in than energy out?

The first thing that happens when we have a negative energy balance is that leptin, the satiety hormone secreted by fat cells goes down. It actually goes down before we lose any fat. Ghrelin, the appetite enhancing hormone goes up.

As the body starts to lose fat several other things happen. The basal metabolic rate decreases. Muscles get more efficient, so the calories we burn per minute of exercise goes down as well. All these changes decrease energy output to try to match the decrease in energy input. This means that fat loss starts to slow down and eventually stop, even though we are eating the same number of calories that caused fat loss in the beginning. Not only does energy output decrease, the body sends powerful signals that increase appetite that make it more and more difficult to keep from increasing our calorie intake. The end result is that 90% of people who lose a lot of fat gain most or all of it back eventually, most within a year. Even more depressing, the low metabolic rate persists even after the fat is regained. Contestants in show The Biggest Loser still had low metabolic rates 6 years after the show, when almost all of them had gained back the fat they lost. In fact, their basal metabolic rates were even lower than when they lost the fat.

I’m sure at this point after hearing all this you are depressed and are saying to yourself, ”what is the point of even trying to lose fat.”

Bad News and Good News

The bad news is that all these mechanisms that operate to make you regain the fat you lost are proportional to the amount of fat you lose. Very fat people who lose enough fat to get close to ideal body fat have an almost impossible time staying there. The body mechanisms that work to bring the body back to the original amount of body fat are just too powerful to resist.

The good news is that permanent fat loss of around 10 percent of your body weight is possible by making permanent changes in your eating and exercise habits. The other good news is that modest fat loss makes a big difference in your risk of high blood pressure, diabetes, heart disease and cancer.

In the next post I will talk about the unconscious mechanisms that contribute to over eating. I will also talk about setting reasonable goals for weight loss and how to go about making permanent changes in your diet and exercise.

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.