Why Am I Gaining Weight for No Reason?

I have heard many women in their 40s, 50s, and 60s ask "Why am I gaining weight for no reason?"

They say that they haven't changed anything but the pounds are steadily increasing.

Some women have expressed gaining 25 pounds or more over the course of a year and they can't figure out why.

It can be demoralizing and confusing!

There are many reasons that people gain weight, of course.

If you can look back and say, "Hey I've been eating a lot and not moving so it makes sense I gained weight.", then that is a different story.

If that is the issue for you, I suggest starting with nourishing your body first before restricting too much.

But that is not what I'm talking about here.

I'm talking about a situation where you truly don't understand why you are gaining weight.

There are various possible reasons that you are gaining weight without an obvious cause.

I'll list some of the most common ones:

  • Chronic stress (1)
  • Poor sleep (2)
  • New medication (3)
  • Recent injury or illness prohibiting normal daily activity
  • Undiagnosed medical condition (4, 5, 6)
  • History of frequent yo-yo dieting (7, 8, 9)

Stress & Sleep

Recently a friend told me that she could not figure out why she had gained 25 pounds in the past 6 months. She said she is exercising regularly and eating a lot of nutritious food.

I asked her if she was under stress or having poor sleep and she said, "all of the above". She said she had been under an enormous amount of stress and her sleep had suffered as a result.

We determined that the stress was probably the culprit so I gave her some stress management techniques and just in the past few weeks she has reported that she has stopped gaining weight.

Of course, this is just one instance. But if you have been under a lot of new stress and/or your sleep has been disrupted then I highly recommend exploring those areas to see if that could be the cause of unexplained weight gain.

New Medication

I once had a client who told me that he gained 40 pounds within 1 year after starting an SSRI (selective serotonin reuptake inhibitor such as Lexapro)!

His doctors were hesitant to change the medication but he finally convinced them and as soon as he switched to a different type of medication he began to lose weight.

Don't discount this possibility and be sure to talk to your doctor if you suspect a new medication is causing weight gain. Many types of medications do cause weight gain and there may be an alternative you can take.

Recent Illness or Injury

When I had Covid last year I didn't feel like myself for at least a month. And as a result, I didn't move nearly as much as I used to.

When I started feeling better I weighed myself and I had gained 5 pounds in one month.

Why was I gaining weight?

Because I normally move a lot! And that had changed.

When you consider why you are gaining weight, think about your recent activity levels and if there is something that has changed.

Undiagnosed Medical Condition

There are a few notable medical conditions that can lead to "unexplained weight gain" such as hypothyroidism (4), PCOS (polycystic ovary syndrome)(5), or depression (6).

So if you are wondering why you are gaining weight then make sure you consider this or any other recent changes in your health or hormones.

Frequent Yo-Yo Dieting

Dieting causes weight gain for many people!

Sometimes a person can yo-yo diet for years and be fine. But that CAN change.

We have had many former yo-yo dieting clients say that they used to be able to lose weight easily but not anymore.

This can be incredibly frustrating but it certainly is a cautionary tale. If you have a history of losing weight and then gaining it back more than two or three times in the past 5 years, please consider an alternative approach.

Yo-yo dieting has been shown to cause weight gain and may answer the question, "Why am I gaining weight for no reason?" (7, 8, 9)

Research shows that restrictive eating causes more hunger and it also causes hormonal changes in the body that favors fat STORAGE!

We all need to stop dieting and start thinking about a long-term strategy that promotes health and then weight loss as a result of improved health.

If you have been gaining weight recently and you are not sure why I urge you to look beyond what you are eating and look at your entire lifestyle.

Note when you started to gain weight and see if you can identify a potential cause such as those listed here.

Your weight is not only about what you eat but also your lifestyle factors so keep that in mind.

If you would like a professional opinion about this and you are interested in embarking on a journey of permanent weight loss, click the link below to learn more about our approach.


  1. van der Valk ES, Savas M, van Rossum EFC. Stress and Obesity: Are There More Susceptible Individuals? Curr Obes Rep. 2018 Jun;7(2):193-203. doi: 10.1007/s13679-018-0306-y. PMID: 29663153; PMCID: PMC5958156.
  2. Kazem YM, Shebini SM, Moaty MI, Fouad S, Tapozada ST. Sleep Deficiency is a Modifiable Risk Factor for Obesity and Cognitive Impairment and Associated with Elevated Visfatin. Open Access Maced J Med Sci. 2015 Jun 15;3(2):315-21. doi: 10.3889/oamjms.2015.063. Epub 2015 Jun 10. PMID: 27275243; PMCID: PMC4877875.
  3. Wharton S, Raiber L, Serodio KJ, Lee J, Christensen RA. Medications that cause weight gain and alternatives in Canada: a narrative review. Diabetes Metab Syndr Obes. 2018 Aug 21;11:427-438. doi: 10.2147/DMSO.S171365. PMID: 30174450; PMCID: PMC6109660.
  4. Laurberg P, Knudsen N, Andersen S, Carlé A, Pedersen IB, Karmisholt J. Thyroid function and obesity. Eur Thyroid J. 2012 Oct;1(3):159-67. doi: 10.1159/000342994. Epub 2012 Sep 22. PMID: 24783015; PMCID: PMC3821486.
  5. Sutin AR, Zonderman AB. Depressive symptoms are associated with weight gain among women. Psychol Med. 2012 Nov;42(11):2351-60. doi: 10.1017/S0033291712000566. Epub 2012 Apr 5. PMID: 22475128; PMCID: PMC3439550.
  6. Glueck CJ, Goldenberg N. Characteristics of obesity in polycystic ovary syndrome: Etiology, treatment, and genetics. Metabolism. 2019 Mar;92:108-120. doi: 10.1016/j.metabol.2018.11.002. Epub 2018 Nov 13. PMID: 30445140.
  7. Sares-Jäske L, Knekt P, Männistö S, Lindfors O, Heliövaara M. Self-report dieting and long-term changes in body mass index and waist circumference. Obes Sci Pract. 2019 Mar 26;5(4):291-303. doi: 10.1002/osp4.336. PMID: 31452914; PMCID: PMC6700513.
  8. Lowe MR, Doshi SD, Katterman SN, Feig EH. Dieting and restrained eating as prospective predictors of weight gain. Front Psychol. 2013 Sep 2;4:577. doi: 10.3389/fpsyg.2013.00577. PMID: 24032024; PMCID: PMC3759019.
  9. Higginson AD, McNamara JM. An adaptive response to uncertainty can lead to weight gain during dieting attempts. Evol Med Public Health. 2016 Dec 5;2016(1):369-380. doi: 10.1093/emph/eow031. PMID: 27920041; PMCID: PMC5139007.
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