Ten Causes of Weight Gain
What Causes Weight Gain?
Maybe you are someone who has struggled with your weight your entire life. Maybe you just recently gained weight and are frustrated at how difficult it is to lose weight! Or maybe you are someone who has never struggled with your weight, but you want to educate yourself on this common struggle. My goal for this post is to review one of the most vital questions we need to ask when discussing weight. What the heck causes weight gain?? Until we know the answer to that question, we can’t even begin to start thinking about reversing it.
Amazingly, this is a question that many of us don’t think about too much because we assume that we already know the answer. Weight gain is caused by eating too much and moving too little. It’s caused by too many calories in, and not enough calories out. Therefore, the answer to how to lose weight must be the opposite: eat less and move more. We have heard this so many times that we don’t even question it. But maybe we should.
As an obesity medicine provider, I used to teach a class called my “into class” to all of my patients before I would meet with them individually, and I started the class by asking everyone to raise their hand if they had heard the statement: “ if you want to lose weight, you need to eat less and move more” and everyone’s hand would go up. And then I would follow that up with: Now keep your hand raised if this strategy has worked well for you. And what do you think happened? People would glance at each other and hands would start to go down, then up a little, and at some point someone would say something like: well, it works at first, but after a while, I just end up gaining all the weight back and then some”. So…it doesn’t really work for most people, at least not in the long-run, right?? And this is NO SECRET! If you’ve had this experience, then join the other 90% of the people who fail to lose at least 10% of their body weight and keep it off for more than a year. And yet, despite the abysmal failure rate of this concept, we continue to push it, and then blame the individual when fail. But maybe they’re not failing. Maybe it’s our understanding of weight and our advice that is failing them! If it was THAT simple, then why do we have over 70% of the adult US population struggling with weight, with 42% struggling with obesity? And why do over 18% of our children have obesity, and why are we seeing increasing rates of 6-month olds with excess weight?? They must be eating too much and moving too little as well! And why have we had such an explosion of obesity in the past 40 years? Clearly, there must be more to it, so that’s what we’re going to be discussing today!
Before we jump into this, I want to have a brief discussion around the word “obesity”. I know that this can be a challenging word for a lot of people, and that it can have a negative connotation and bring about feelings of shame for some. I will be using this word because it is the medical term that we have for the condition where a person has excess weight that is harming their health or quality of life. It is not to be used as a descriptive factor, nor does it define who or a person is. My hope is that I can help explain to you why obesity is a chronic medical condition, and that we can learn to think and talk about obesity without the shame, blame, and guilt around it. Like diabetes, back pain, hypertension, or any other medical condition, obesity is not a personal choice, a character flaw, or caused by lack of willpower. It is not the individual’s fault. There are lifestyle factors involved with obesity, as there are with most other chronic medical conditions, but unlike other medical conditions, most people with obesity feel that it is entirely their responsibility to manage this medical condition. Unfortunately, many health care providers don’t go beyond advising weight loss, and the unhelpful recommendation to eat less and move more. They also expect the patient to treat their own medical condition. This is not expected with any other disease state. Obesity is recognized by the World Health Organization and by the American Medical Association as a medical condition, and it is something that the right health care provider can help you with.
I’d like to start with the definition of obesity, according to the Obesity Medicine Association. According the them, “Obesity is defined as a chronic, progressive, relapsing, multi-factorial, neurobehavioral disease, wherein an increase in body fat promotes adipose tissue dysfunction and abnormal fat mass physical forces, resulting in adverse metabolic, biomechanical, and psychosocial health consequences.”.
Wow, that’s a mouthful and probably doesn’t mean anything to anyone other than people trained in obesity medicine! But what it says is incredibly important, and I will break down this definition for you so that it WILL make sense to you, because there is a lot of science and truth held within this definition. Today we will focus primarily on the “multi-factorial” part of the definition.
Obesity is a multifactorial medical condition. That means that there are many, many different factors that go into whether a person gains weight and develops obesity or not. We will touch on some of the most common factors today, but know that there are many more factors, and that entire books can be written on just this topic alone. Today, we will cover ten factors that can contribute to weight gain.
1. Genetics
One of the factors that determines someone’s risk for developing obesity is genetics. Genetics explain about 40-70% of variance in weight. There are hundreds of genes that have been identified that can contribute to weight gain, and the more of those genes a person has, the higher the likelihood that a person will develop obesity.
While there are a few, rare single gene causes of obesity, most of the time it’s a combination of multiple genes that can predispose someone to obesity. What is important to recognize about genes, however, is that they do not determine your destiny. Genes are like light switches that can be turned on and off. Genetics may create the predisposition for someone to develop obesity, but if the right environment does not exist to turn these genes on, the person will likely NOT develop obesity. In other words, genetics load the gun, but it’s the environment that pulls the trigger.
In the “right” environment for weight gain, such as the one we all live in today, many of us have the genes to gain weight. Why do so many of us have these genes? Because the ability to gain weight when food is plentiful is what allowed our ancestors to survive periods of famine and harsh winters. It’s important to remember that we spent 99.5% of our human history as hunter-gatherers. However, our environment has changed rather drastically in the past 10,000 years since the agricultural revolution, and even more rapidly in the past 40 years. The environment that we currently live in is the perfect environment for weight gain for most of us!
Time-traveling back to our caveman days is not an option, and the idea of chasing after squirrels in the backyard for dinner does not sound very appealing. We can’t change the genes we were born with, but we CAN create an environment for ourselves that incorporates some of the lifestyle factors that our biology depends on for optimal health. That brings us to epigenetics.
What in the world is epigenetics? It’s basically the study of how our environment affects our genes without changing the genes themselves. If our genes load the gun, it’s epigenetics that pulls the trigger. Or, if you prefer the light-switch metaphor: Epigenetics is what turns the light switches that are our genes on and off.
The number of things in our environment that can affect our weight is almost infinite, but let’s tackle a big one first:
2. Nutrition
The effects of nutrition on weight has been dumbed down to a simple matter of calories, but the truth is that nutrition is so much more complex than that. Nutrition plays a hugely important role in the function of our genes and our biology. Unfortunately, there is insufficient time spent in medical training on the topic of nutrition and its impact on health. What I remember from my medical training on nutrition is that it’s all about “balancing” your calories in and calories out, that you should eat a low-fat diet. I also learned about vitamin deficiencies that we rarely see in industrialized countries. What I didn’t learn about is how various nutrients affect health and well-being, and how nutrition can cause disease, or prevent and even reverse disease!
What we consider “normal” nutrition in this day and age is anything but “normal” for our human body and our genes. Over 60% of calories consumed in the US come from ultra-processed foods- foods that are made in factories with loads of additives and chemicals, that our body hardly recognizes as food. And 80% of processed foods have sugar added to them. Eight out of ten products in grocery stores did not exist 100 years ago. Not only does this type of “food” lack nutrition and contain harmful substances that cause disease, it also causes us to overeat and can put our fat storage into overdrive. I will be discussing nutrition in detail in future posts, but for today, I just want us to recognize that our nutrition affects our biology on many different levels that go far beyond calories.
3. Activity
Next: another one that is familiar to many of you: activity, or rather, lack thereof. This one is also frequently reduced to “calories out”, but once again, the impact of activity on our biology goes far beyond mere calories. Perhaps you have heard that “sitting is the new smoking”. That saying comes from the many negative health outcomes associated with sitting. Even if we exercise before we spend our day sitting, the exercise does not off-set many of the health risks associated with sitting. Activity is another topic that I’ll go into in WAY more detail, and there are many myths surrounding activity that require some busting. I’ll give you a quick example: exercise is not very effective for weight loss. There. I said it. It’s true. However, that does not mean that we should throw activity out of the window. We need to remember what this is about: it’s about GAINING HEALTH, and activity it is CRUCIALLY important for your physical and mental health. It is imperative for communication between your muscles and the rest of your body. Also, I should note that exercise IS particularly important for weight maintenance.
So far not too many surprises: nutrition and activity are important components of our health and determinants of weight. Some of these next few factors, however, may be new to you.
4. Bacteria and Viruses
Trillions of bacteria in your gut make up your “microbiome”. The number if bacteria in your gut outnumber your own cells by 10:1, and the genetic material of these bacteria outnumber your own genes 100:1. These gut bacteria play a hugely important role in our overall health, AND on our weight. There are two main bacteria in our microbiome that make up 90% of the bacteria, and these two types are called “Firmicutes” and “Bacteroidetes”. Firmicutes are much better at extracting calories out of the food you eat, and surprise surprise, people who struggle with obesity (and this is also seen in type 2 diabetes) have higher levels of Firmicutes and lower levels of Bacteroidetes compared to lean individuals. So, this means, that two people can eat the same food, but one person extracts more calories out of that food than the other person. Whoa, crazy, huh? In mice, transplanting the microbiome of a lean mouse to a mouse with obesity and vice versa caused the lean mouse to gain weight and the mouse with obesity to lose weight. Unfortunately, so far, studies have not been able to show the same result in humans. We have learned much about the microbiome in the past 10-20 years, but there is still much more to learn. For now, we’ll just keep in mind that the bugs that live in our guts affect our overall health and our weight. There are many environmental and lifestyle factors that affect our microbiome, so we will be discussing that in more detail in the future as well.
Speaking of bugs, did you know that there is a virus that can cause weight gain? Yep, adenovirus-36 causes obesity in both humans and animals. It increases the amount of glucose that the cells take in, and increases the development of fat cells, or adipocytes. It is estimated that around 30% of people with obesity in the US are infected by this virus, compared to 11% of people with normal weight, and that there is a strong correlation between infection with this virus and the development of obesity.
Okay, still believe that it’s just about willpower or calories? Let’s keep going then.
5. Weight-promoting Medications
A 2010 study found that the number of Americans using five or more prescription drugs increased 70 percent over the past 10 years. While many recognize the financial impact and the potential for side effects this can have, there is a common side effect of many medications that people may not be aware of. You guessed it. It is WEIGHT GAIN! I am not suggesting that anyone stop taking their medications without discussing with your prescriber first, but this is an important aspect to consider when looking for potential causes of weight gain. Your health care provider may be able to help you find alternative medications that do not cause weight gain and can sometimes even help with weight loss! Other times, there are medications that we simply need to stay on because their benefits outweigh the potential weight affects. It’s important to note that it is possible to manage one’s weight despite being on a weight-promoting medication. However, it is important to acknowledge that this could be a factor affecting someone’s weight.
6. Endocrine Disrupting Chemicals
Another one that may surprise you: chemicals that are in our household products, our food and food packaging, our cosmetics and personal care products can cause weight gain. These chemicals also include fire-retardants in fabrics, clothing, and furniture. The medical term for these chemicals is “endocrine disrupting chemicals” or “obesogens”, and these chemicals are all around us, all the time. We are especially susceptible to the effects of these chemical in-utero (during pregnancy), and during early infancy. Not only do these chemicals cause us to develop increased body fat, but they are also stored in our fat, creating a vicious cycle of more weight gain and other negative health consequences, including the development of certain cancers. These chemicals interfere with the control of energy metabolism and the way your body regulates your fat cells, shifting the balance towards weight gain and obesity, despite normal diet and exercise patterns.
7. Hormones and Neurotransmitters
While we are on the topic of hormones, let’s talk about hormones! Hormones are SO important when we talk about weight. Hormones are what DRIVE weight gain or weight loss. Think about it- any growth that happens in the body is caused by hormones, and the growth of our fat tissue is NO different.
Why do kids grow? They grow because their body is producing GROWTH hormone. They then EAT more because they are GROWING. Think about a pregnant woman- the baby inside her womb is growing because of hormones being released, NOT because the mother is eating more. In fact, she eats more BECAUSE there is a child growing inside of her. Can you see what I am getting at here?
So, what causes us to gain weight?? Hormones! The primary hormone that causes fat storage is insulin. We have known for MANY years that insulin is the hormone that controls fat metabolism. Insulin is the hormone that tells your body to store fat, and prevents you from using fat, including stored fat, as a fuel source, essentially locking your fat inside your fat cells. And what do we see repeatedly in people who struggle with weight?? Chronically high insulin levels. Their insulin levels are elevated even when they are in a fasted state, meaning that they are ALWAYS IN FAT STORAGE MODE! How can you do anything BUT gain weight??
Chronically high insulin levels makes you freaking hungry all the time, because you can’t tap into your fat stores to hold you over between meals, which means you get ravenous every few hours as your glucose dips and your body has no access to alternative fuel sources. And not only that, but there is an interplay between insulin and your other hormones that control appetite, such as leptin. Leptin is a hormone that is secreted by your fat cells, which informs your brain about the level of your fat stores.
Wait, what? There are hormones that tell your brain about your fat stores? Yep! And not only that, your appetite is determined by hormones as well. Yes, your appetite is driven by powerful hormones that act on the brain.
People who struggle with weight develop not just insulin resistance, but leptin resistance as well, which means that their brain is not receiving signals from your fat stores to tell you that you have enough fat stores. The result? Again, increased hunger.
In recent years, researchers have also shown that people affected by obesity may have different levels of other appetite regulating hormones such as ghrelin and GLP-1, increasing appetite. Studies also show that some people are more susceptible to cravings and the desire to eat certain foods.
Cravings also come from the brain, but from a different part of the brain than your appetite control center. Cravings and emotional eating lives in the reward center of your brain and has to do with neurotransmitters like dopamine and your opioid receptors. This is why we decide to eat that slice of pumpkin pie after Thanksgiving dinner: it ain’t cause you’re hungry. That’s your Reward Center talking! This world of hormones that affect our appetite is vast and fascinating, and we will be spending a significant amount of time discussing these in the future, so if you want to hear more, stay tuned!
8. Sleep
Lack of sleep, or poor quality of sleep causes weight gain, as does a medical condition called obstructive sleep apnea. When we are sleep deprived, our body produces more hormones that makes you hungry, and less hormones that tell your brain that you are satiated. Sleep affects your genes as well. Just one week of sleep deprivation alters the function of 711 genes. Your insulin sensitivity goes awry after just 4 days of insufficient sleep. It even affects your ability to lose weight, even if your calories stay the same. This is why it is so important to try to get 7-9 hours of sleep each night, and to get tested for medical conditions such as sleep apnea. If you struggle with insomnia, talk to your health care provider about this. There is help!
9. Medical Conditions
There are a host of medical conditions besides sleep apnea that can contribute to weight gain. These medical conditions can easily be screened for and be treated. Medical conditions that can cause weight include hypothyroidism, Cushing’s syndrome, depression, and, as already discussed, insulin resistance and sleep apnea.
10. Stress
And then of course there is our dear friend stress, which can cause weight gain in several ways. For one, cortisol, our stress hormone, causes weight gain and insulin resistance when it is chronically elevated. Secondly, 80% of people change their eating behavior when stressed, and for many, that means increasing their food consumption, especially foods that light up the “reward center” of our brain, such as sugary, starchy, and high fat foods.
What I want you to take away from this is the following: There is a lot more to weight management than “calories in-calories out”. Some of these things, such as the genes you were born with, are outside of your control, but at least you can stop blaming and shaming yourself that “you did this to yourself”.
Also, I hope you take away that there are a lot of these factors that we CAN control, such as our nutrition, activity, sleep, medical conditions, medications, and managing our stress! We now also have medical and surgical treatment options to help with appetite control! Asking for help from a medical provider does not mean that you are weak or taking the easy way out. You are simply seeking medical assistance for a chronic medical condition which very few people can successfully manage on their own.
Now that we have a better understanding of the underlying causes of weight gain, we can start to develop strategies that WORK! We can start to chip away at the antiquated manta of eating less and moving more. We can stop the blame and shame game, so that you can be empowered to live YOUR healthiest life!