Grandmother, mother, and daughter posing for picture (illustrating genetics as a factor that can influence weight loss)

What factors influence weight loss?

Written on February 6, 2023 by Amy Harris, MS, RN, CNM. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.

Table of contents

If only losing weight was as simple as a math problem — you subtract more calories than you add, leaving you with a deficit. The answer? You lose weight.

Unfortunately, weight loss is much more complex and different for every person. How you lose weight and keep it off can be determined by your genes, your diet, your physical activity, your environment, and many other factors. So, what factors influence weight loss? Here, we’ll review five often-overlooked influencers of weight loss, so you know what matters when trying to lose weight.

Five lesser-known factors influencing weight loss

We know that the key ingredients for maintaining a healthy weight are a recipe of regular physical activity, healthy eating patterns, and low-stress living practiced day in and day out for a lifetime, not just for a few months [1]. However, beyond diet, exercise, and stress, obesity researchers have identified several other factors that can affect weight loss. The five we’ll tackle in this post are:

  • Your family and your genes
  • Medical conditions or medications
  • Your gut and microbiome
  • Your mental health
  • Your sleep

Your family and your genes

Take comfort in knowing that your challenges in losing weight despite doing everything right may lie in your genes. Genes (inherited from your parents) function like a blueprint directing how your body runs. They are one of the most significant determinants of obesity and your ideal weight, often called your setpoint [2]. Researchers have identified multiple different genes that can control [2-4]:

  • How your body responds to hunger cues
  • How much and where fat gets stored
  • How your body responds to caloric restriction or increased exercise
  • Your body composition (lean muscle mass)
  • How you respond to a low-carbohydrate diet (like a keto diet) or intermittent fasting

It is not only your family’s genes that determine your weight — medical conditions (both inherited and not) can influence your weight loss success as well.

Medical diseases and medications that hinder weight loss

Any condition that makes you want to move less or makes sustained physical activity challenging can make it harder to lose weight. Examples include arthritis, long COVID, cardiovascular disease, and cancer, just to name a few. Studies consistently show that people who move less gain more weight [5].

Thyroid disease is another common medical condition that can cause either weight loss or weight gain. Thyroid disease is very common — an estimated 20 million people in the United States have some type of thyroid disorder [6].

Another hormonal condition that makes weight loss hard for people with ovaries is Polycystic Ovarian Syndrome (PCOS). People with PCOS are more likely to be insulin resistant, leading to more fat being stored around their torso and difficulty losing weight.

Many medications can cause weight gain or make it harder to lose weight. It is always a good idea to ask your healthcare provider how any new prescription could affect your weight. Below are just some of the most commonly prescribed medications that can cause weight gain [7]:

  • Steroids (arthritis, asthma, skin conditions)
  • Antipsychotics (depression, bipolar, schizophrenia)
  • Injectable insulin (diabetes)
  • Sulfonylureas (diabetes)
  • SSRI antidepressants (depression)
  • Beta-blockers (high blood pressure)
  • Some migraine medications

Could poor gut health be sabotaging your weight loss attempts?

Maybe. The collection of bacteria, fungi, and other organisms living in your intestines (called the gut microbiome) is affected by what you eat. The health of your gut microbiome may contribute to weight gain or difficulty losing weight [2]. Another study showed that people with obesity were more likely to have an unhealthy mix of bacteria in their gut than people at a healthy weight [8]. Research on how adding things like prebiotics, probiotics, more fiber, and fermented foods could help you lose weight is ongoing, so stay tuned!

Mental health is connected to weight loss success

The relationship between mental health and weight maintenance can be complex. Research has shown that people with poor mental health, anxiety, or depression are two to three times more likely to develop obesity and related disorders such as diabetes and heart disease [9]. In addition, living in a larger body can negatively affect mental health because you experience more bias and stigma [2].

The mind-body connection is real when it comes to finding your healthiest weight. For example, some people with clinical depression lose weight while others gain weight. In addition, treating mental health conditions such as anxiety or depression, either with counseling or medications, can increase your chances of successfully maintaining a healthy weight [10].

Loneliness and a lack of social connection are both risk factors for obesity. Support systems (like checking in monthly with your Everlywell weight management nurse practitioner) contribute to weight maintenance after successful dieting [11].

Sleep matters too

The interplay between your sleep and mental health, in turn, impacts your weight. For example, people who get less than 6 hours of shut-eye a night tend to have more body fat. This is because lack of sleep can cause your body to make too much of the hormones cortisol and insulin, which can add pounds. In addition, disrupted sleep cycles mess with hormones that signal hunger and make you crave foods loaded with fat and sugar [2].

Weight management needs to be personalized for each body

The complex and unique interplay between your genes, environment, diet, and lifestyle means you will most successfully lose weight when your weight loss plan is personalized. That is why Everlywell offers access to affordable weight management support provided by licensed nurse practitioners via telehealth. Backed up by a suite of at-home laboratory tests, vitamins, and supplements, Everlywell is here to support you throughout your weight loss journey.

Do men or women have an easier time losing weight?

Does weight loss get harder with age?

When to stop intermittent fasting: what you need to know

How much is enough when looking to lose weight?

How to start a weight loss journey: key steps


  1. Losing weight. CDC. Published September 19, 2022. Accessed February 1, 2023. URL.
  2. Obesity. Mayo Clinic. Published September 2, 2021. Accessed February 1, 2021. URL.
  3. Hinney A, Körner A, Fischer-Posovszky P. The promise of new anti-obesity therapies arising from knowledge of genetic obesity traits. Nat Rev Endocrinol. 2022;18(10):623-637. doi:10.1038/s41574-022-00716-0.
  4. Factors affecting weight and Health. NIH-NIDDK. Published February 2018. Accessed February 2, 2023. URL.
  5. Ladabaum U, Mannalithara A, Myer PA, Singh G. Obesity, Abdominal Obesity, Physical Activity, and Caloric Intake in US Adults: 1988 to 2010. The American Journal of Medicine. 2014;8: 717-727. URL.
  6. Thyroid disease. Cleveland Clinic. Published April 19, 2020. Accessed February 1, 2023. URL.
  7. Goad, K. 5 Medications that can cause weight gain. AARP. Published May 18, 2022. Accessed February 1, 2023. URL.
  8. Gao R, Zhu C, Li H, et al. Dysbiosis Signatures of Gut Microbiota Along the Sequence from Healthy, Young Patients to Those with Overweight and Obesity. Obesity (Silver Spring). 2018;26(2):351-361. doi:10.1002/oby.22088.
  9. Ma J, Rosas LG, Lv N, et al. Effect of Integrated Behavioral Weight Loss Treatment and Problem-Solving Therapy on Body Mass Index and Depressive Symptoms Among Patients With Obesity and Depression: The RAINBOW Randomized Clinical Trial. JAMA. 2019;321(9):869–879. doi:10.1001/jama.2019.0557.
  10. Littleberry M. Obesity and mental health: Is there a link? Obesity Action Coalition. Published December 2017. Accessed February 1, 2023. URL.
  11. Maintaining weight loss. Johns Hopkins Medicine. Accessed February 1, 2023. URL.
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