Last Updated on June 29, 2022 by Rebecca Huff
If you are medically overweight, like 39% of the world’s population, you might be asking yourself, “what causes weight gain?”
You may be here because you’re trying to lose weight. More than half of Americans are currently attempting to lose weight on any given day of the year. (1)
Ask most doctors what causes weight gain or the inability to lose weight and you’ll likely hear that the number of calories you consume exceeds the number you burn. Not as commonly, you may hear about other possible causes such as too much of the stress hormone cortisol.
Though conventional medical advice often associates weight gain with overeating, lack of physical activity, too much snacking, and other “mistakes” on your part. You may even experience bias from your physician. (Do a search for “are doctors biased against overweight and obese patients” to see for yourself.)
One of the primary reasons for weight gain is diet culture.
“You Must Be Doing Something Wrong”
Recently, I went to an orthopedic doctor because I’d been having some pain in my left foot. We met for the first time after an x-ray. She made her diagnosis within the first 3-5 minutes of being in the room. The conclusion was that I had a simple case of nerve entrapment.
The doctor wanted to give me a steroid shot, but I declined and explained that I just wanted to know what was causing the pain. With this information, I could start working on whatever was going on.
In addition, expressed concern that my gradual weight gain since my early forties might be a contributing factor to my foot pain.
This brings me to the topic of this post.
At the end of a visit that lasted all of 7 minutes tops most of which we spent talking about my foot, she had sized me up.
The tall, thin, elderly female doctor explained that my weight gain wasn’t normal. She further elaborated that there had to be something I was “doing wrong” if I’d been steadily gaining weight. Either I was eating too much, not the right thing, or more than the energy I was using up.
Is it really that simple? No.
Overweight and obesity are complex issues and are rarely as simple and straightforward as this particular doctor suggests. Just because you're overweight doesn't mean you're doing something wrong.
What causes weight gain?
Some studies indicate that overweight and obesity may have plenty to do with our genetics. Gene variants studied show women with certain alleles have more fat mass and a lowered ability to burn it off.
Genetics and Body Weight
Conflicting studies from around the world make it hard to say for sure if there is a correlation between single nucleotide polymorphisms (SNPs) and obesity. Your body may do better on certain types of diets due to your genes. You can find out using SelfDecode.
Though we do know that hormones play a major role in weight issues. Leptin and Ghrelin are worth studying if you struggle to lose weight. Read “it’s not your fault you are overweight.”
You may notice you gain weight like your parents or grandparents, as I do.
My maternal grandmother, who I have no doubt had undiagnosed blood sugar issues, gained weight in her arms and around the middle. (She didn’t like to go to the doctor, but had all the symptoms of blood sugar imbalances.)
Like my grandma, the weight I gain tends to accumulate in my arms as well. Unlike my grandmother, I have enviable A1C results. (A1C is a simple blood test that measures your average blood sugar levels over the past 3 months. It is a more accurate measurement of true blood sugar levels than daily glucose testing, which I also do 2-3 times per month.)
Another reason for frustration with the orthopedic doctor’s suggestion; she doesn’t know anything else about my health. Her assessment was based on my foot x-ray and my appearance. I’m overweight.
Does Metabolism Slow As We Age?
A new study implies previously accepted theory on weight gain with age may be incorrect.
The study proposes metabolism does not slow down as we age; at least not until we’re over 60.
It’s a bit hard for me to believe the old theory that metabolism slows and weight gain as we age is inevitable is outdated and wrong.
When I was a teenager through my twenties and even into my thirties, I was in the “healthy” weight range according to my BMI. During my teens and twenties, in the ’80s and ‘90s, I ate a Standard American Diet. What I mean by that is that I ate an occasional fast food meal or soda, added sugar to my coffee, and kept processed foods in my pantry. I ate ice cream when I wanted to and cake too. Yet I stayed in the “healthy” range.
During my late 30s and throughout my 40s my diet changed for the better as I studied dietitian courses. Now, at 50, I eat predominantly whole foods, rarely ever eat out, and never at fast-food restaurants.
I gave up soda in 2003 at the age of 32. Around that time I quit sugar, white flour, and fast food.
My diet improved. Yet, after a decade of eating healthily, the extra pounds came on each year. I’d mentioned my weight to the orthopedic doctor only to find out if it could be related to the nerve entrapment. Yet her response was to tell me that I was doing something wrong and that my weight gain is the result.
It was disheartening, yet deep down I believed her.
Most of us tend to believe our weight gain is all our fault, even if we are doing the best we can. I sat there blaming myself, all while knowing my primary doctor who I’ve seen for over 10 years says most people tend to gain weight as they age and it’s hard to lose and keep it off. Especially during menopause.
Overweight and Obesity are Getting Worse, Not Better
In 2022, more people have excess weight than ever before. The number of people who are considered obese has tripled since 1975. (2) The U.S. adult obesity rate stands at 42.4 percent, the first time the national rate has passed the 40 percent mark, and further evidence of the country’s obesity crisis. (3)
According to a Gallup poll, nearly half of America’s overweight people don’t realize they’re overweight.
In broaching a discussion of excess body fat and its associated health complications practitioners are encouraged to avoid using undesirable terms — such as “obesity” or “fatness.” Use of such terms may offend or distress some patients and prevent them from continuing to discuss their weight. We encourage health care providers to use patient-friendly terms, such as “weight,” “weight problem,” or “BMI,” when broaching the topic of weight with their obese patients. (4)
Epidemiologists conclude most of us will gain 1 to 2 pounds a year from early adulthood through middle age. Although newer studies suggest that metabolism doesn’t slow as we age as previously believed.'
Energy Intake vs. Energy Expenditure
New information is challenging what has been believed about calories in vs. calories out. Some scientists now believe that overeating isn't the primary cause of obesity. If you're a person who “eats right and exercises” and still doesn't lose weight, you might find this information valuable. (If this is you, listen to the podcast at the top of this post, or watch the video linked at the bottom.)
Adoption of the carbohydrate-insulin model over the energy-balance model has radical implications for weight management and obesity treatment. Rather than urge people to eat less, a strategy which usually doesn't work in the long run, the carbohydrate-insulin model suggests another path that focuses more on what we eat.
Your Basal Metabolic Rate can change and does depend on a variety of factors. So while calories in vs. calories out is a factor, there are variables. These include gender, genes, medications, fat tissue, lean tissue, body size, illness, and more.
BMI really shouldn’t be considered the gold standard for measuring a healthy weight. Body Mass Index doesn’t take into account a person’s body fat versus muscle (lean tissue) content. Although the NIH and CDC still promote BMI as a fairly reliable indicator of healthy weight, overweight, and obesity.
The Waist to height ratio is a better predictor of heart disease and diabetes risk than BMI, according to new research presented at a scientific meeting recently.
For example, if you are 65” tall your waist circumference should be below 32.5” measuring mid-way between the lower rib and the iliac crest. WHtR (waist to height ratio) is better at predicting risks of cardiovascular disease and diabetes, and of overall mortality according to the World Health Organization.
Surprising causes of weight gain
Yes, it is true that a sedentary lifestyle and too much food can cause weight gain. But what if you’re eating a healthy diet, staying active, and still gaining weight?
Surprisingly, eating too little can slow down your metabolism and trick your body into thinking it’s in starvation mode. Food quality and quantity both matter. Also, eating too fast and not chewing thoroughly can also be contributing factors.
It’s worth exploring with lab work. Your doctor can order tests to check for endocrine disorders. Excess cortisol, thyroid disorder, or other hormone imbalances should be ruled out before you blame yourself.
Mineral imbalances can cause water retention which may make you look and feel puffy. Too much salt, not enough magnesium, or dehydration may be the culprits.
In addition may gain weight due to other health conditions such as PCOS, congestive heart failure, or type 2 diabetes.
Lack of sleep not only impacts your well-being but can also lead to extra pounds. Insufficient sleep can cause you to turn to junk food when you’re overly tired and moody.
In addition to flat out missing sleep, using devices with blue light before bedtime can mess with your circadian rhythm and lead to poor sleep which contributes to weight gain.
Practicing good sleep hygiene contributes to a healthy metabolism.
Imbalance in Gut Bacteria
Another sometimes overlooked cause can be an imbalance in the gut microbiome. Your metabolism will suffer in spite of healthy eating if you lack the right kind of gut bacteria.
A variety of factors may be at play including whether you were born via c-section or vaginally, the use of antibiotics, and where you’ve traveled!
Consume plenty of pre and probiotics to prevent bloating, constipation, excess weight, lethargy, and other symptoms of poor gut health. You can get more out of your probiotics if you pair them with prebiotics. In fact, in many cases, starting with prebiotics is preferable.
These can come from foods such as asparagus, artichokes, and other foods or you can consume a prebiotic supplement such as Layer Origin’s HMO powder.
The first time I took HMO powder, I lost 10 pounds in around two weeks without altering my diet in any way or adding exercise. That was a surprise to me, but when I started reading more about it, the weight loss made perfect sense.
HMO stands for Human milk oligosaccharides, you can find out more about them here: HMOs: The Missing Key to Better Health That You May Have Overlooked.
Even though I eat lots of vegetables and fermented foods. Taking the super prebiotic made a big difference.
Now I take Layer Origin's Pure HMO Beauty Mix which contains prebiotic powder, along with collagen peptides and hyaluronic acid. The HMO prebiotic helps with immune health as well as IBS symptoms, leaky gut, and overall wellness. Since I stopped dieting and started eating intuitively and caring for my health, my weight stabilized.
Side Effect: Weight Gain
You may have a health condition that is causing fluid retention, constipation or loss of muscle mass. The medication you take may also be causing weight gain. Check with your doctor or read the insert or pamphlet scanning for weight gain as a side effect.
Some medications such as birth control pills or antidepressants may cause weight gain (although others may cause weight loss.) Corticosteroids are one of many medications that may result in weight gain.
Before blaming yourself for weight gain, explore the possibility that it is a side effect of something rather than the issue.
Causes of Weight Gain
In the case of sudden weight gain, your doctor may suspect an underactive thyroid gland or other medical conditions. Cushing’s syndrome, polycystic ovary syndrome, and even sleep apnea may be underlying causes of sudden weight gain.
So many factors can contribute to weight gain and make weight loss difficult. Medical conditions are at the top of the list.
- Type 2 Diabetes
- Age-related muscle loss
- Genetic Factors
- Lifestyle changes (people tend to be less active as they age)
Too much of the hormone cortisol can contribute to body fat, in particular around the waistline. This happens when the adrenal glands become fatigued. A simple lab test can help you find out if you are producing too much or not enough cortisol. Both can be problematic and lead to weight gain.
Weight Gain Before, During, and After Menopause
Throughout a woman’s life hormones play a role in weight gain. Particularly around menopause, women may gain weight or have difficulty losing.
The right exercise paired with mindful eating or intuitive eating can be helpful during this stage of life.
Psychiatric disorders such as depression, attention deficit disorder, and post-traumatic stress disorder can lead to weight gain owing to “comfort eating,” a lack of interest in preparing healthy meals, and impulsive eating habits. (5)
Healthy Eating and Still Gaining Weight
If you practice healthy eating, stay active, have tried diets, and still struggle to lose weight or even gain, I hope that this sheds some light on possible contributing factors. It’s important not to stress or beat yourself up if you’re in this category. Stress can even lead to high blood pressure and a cascade of other issues.
A few years ago, I chose to stop dieting as it was taking a toll on my mental health. When I quit dieting, my weight stabilized. I still need to lose some weight, but at least I stopped gaining. (Even though I don't diet, healthy eating habits have been part of my life for decades. Eating vegetables at every meal, including high fiber foods and good sources of protein, etc. are just part of my normal life.)
For years I hated myself because I was a few pounds overweight. That started a process of dieting that is counterproductive. It is tough to recover from that mentality. The more you diet and stress over your weight, the harder it is to do something about it. Instead of focusing on weight, shifting your focus to restorative activities is healthier.
It’s challenging to learn to love yourself and let others love you when you believe your weight is somehow tied to your worth.
Dieting is an exhausting cycle that puts major stress on your nervous system keeping you in a horrible fight or flight mode.
Investigate underlying causes for weight gain
Work with a functional medicine doctor to explore possible underlying causes. Once you’ve ruled out or identified possible causes, you can focus on health markers instead of the scale or size of your jeans. Then you can enjoy the nutritious foods you love.
In my situation, mold illness, lyme disease, and glyphosate toxicity paired with other health conditions, age were all factors.
The unfortunate truth is that what causes an individual to gain weight may be as varied as are people.
Books I recommend on the subject of learning to eat intuitively without dieting:
- Health at Every Size: The Surprising Truth About Your Weight
- The Binge Cure: 7 Steps To Outsmart Emotional Eating
- The Intuitive Eating Workbook: Ten Principles for Nourishing a Healthy Relationship with Food
The information, including but not limited to, text, graphics, images and other material contained on this website are for informational purposes only. No material on this site is intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or another qualified healthcare provider with any questions you may have regarding a medical condition or treatment before launching a new health care regimen, and never discount professional medical advice or delay in seeking it because of something you have read on this website.
- Martin CB, Herrick KA, Sarafrazi N, Ogden CL. Attempts to lose weight among adults in the United States, 2013–2016. NCHS Data Brief, no 313. Hyattsville, MD: National Center for Health Statistics. 2018.
- “Obesity And Overweight”. Who.Int, 2022, https://www.who.int/news-room/fact-sheets/detail/obesity-and-overweight.
- “The State of Obesity 2020: Better Policies for a Healthier America.” Tfah, https://www.tfah.org/report-details/state-of-obesity-2020/.
- Volger, Sheri et al. “Patients' preferred terms for describing their excess weight: discussing obesity in clinical practice.” Obesity (Silver Spring, Md.) vol. 20,1 (2012): 147-50. doi:10.1038/oby.2011.217
- Mental Illness and Obesity – Psychiatry Advisor. https://www.psychiatryadvisor.com/home/conference-highlights/aaic-2015-coverage/mental-illness-and-obesity/
- Kotzampassi, Katerina et al. “Obesity as a consequence of gut bacteria and diet
- Scientists claim that overeating is not the primary cause of obesity– https://www.sciencedaily.com/releases/2021/09/210913135729.htm
- Turnbaugh, Peter J et al. “A core gut microbiome in obese and lean twins.” Nature vol. 457,7228 (2009): 480-4. doi:10.1038/nature07540
- Elison, Emma et al. “Oral supplementation of healthy adults with 2′-O-fucosyllactose and lacto-N-neotetraose is well tolerated and shifts the intestinal microbiota.” The British journal of nutrition vol. 116,8 (2016): 1356-1368. doi:10.1017/S0007114516003354