When researchers ask people why they want to lose weight, perhaps the most common answer is that they want to improve their health (e.g., O’Brien et al., 2007). This is a great pattern to see! People who are, instead, primarily motivated by “looking good” tend to have less autonomous motivation in their attempt(s) to lose weight, meaning that long-term persistence in their weight loss journey is less likely (Teixeira et al., 2012).

The lesson here is clear: if you want to succeed in losing weight, it is a good idea to focus on your own personal improvement rather than what other people think of you. So today, let’s focus on 3 reasons — with scientific evidence! — that a person’s health improves after losing weight.

Reduced Cancer Risk

When a person develops cancerous growths in their body, what has typically happened is a transcription error at the level of their genetic material. Usually, a person’s DNA replication and other transcription systems excel at catching such transcription errors and correcting them before cancer can develop as a result. However, a mistake slips through every once in a while, resulting in mutant molecules (e.g., proteins) in a process called “transcriptional mutagenesis” (Brégeon & Doetsch, 2011). These mutants can promote the growth of cancerous cells.

One theoretical reason why weighing more, especially being obese, increases the risk of cancer is that when your body weighs more, it contains more cells that are transcribing genetic information. Therefore, more transcription errors slip by undetected.

However, this increase in transcription mutagenesis only explains the existence of cancer in the body in the first place. Obesity also promotes cancer once it exists in the body. The mechanisms by which it accomplishes this are not well understood, but involve inflammation and hormone balances that somehow encourage the growth of the cancer (Vucenik & Stains, 2012). Weight loss seems to cut down on the risks significantly, at least for certain cancers such as prostate and breast.

Improved Sleep

The amount of time that a person spends sleeping at night has a direct relationship to how much they weigh. If a person wants to get enough sleep, it is beneficial for them to weigh a healthy amount. Interestingly, this relationship seems to go both ways, such that a person who gets better sleep is less likely to be obese, and a person who is less obese is more likely to get better sleep. Some specific examples include longer sleep durations when a person has lower Body Mass Index (BMI), and an increased likelihood of being obese if they get insufficient sleep — defined as less than 6 hours per night (Beccuti & Pannain, 2011).

One reason for this relationship between weight and sleep has to do with Obstructive Sleep Apnea (OSA). OSA occurs when a person’s airflow is disrupted during sleep, often due to throat muscles constricting. This leads to loss of sleep quality as well as snoring in some people. One big reason why OSA is so disruptive to sleep is that it reduces the amount of oxygen in your blood, which forces your brain to wake you up briefly in order to fix your breathing. These brief awakening are frequently not remembered by the sleeper, but they lead to drowsiness the next day.

Obesity seems to increase the risk of OSA thanks to greater breathing obstructions , and OSA seems to increase the risk of obesity thanks to drowsiness leading to less energy expenditure following the sleeping period (Beccuti & Pannain, 2011).

A study that followed people who had lost weight found that losing greater than 5% of a person’s body weight was associated with short-term improvements in sleep duration and sleep quality (Alfaris et al., 2015). In other words, losing a few pounds can lead not only to longer nights of sleep, but to more restful sleep as well.

Better Memory

Negative old-age memory outcomes, including the development of Alzheimer’s disease, are associated with obesity in middle age. Fortunately, weight loss in obese people has been shown across multiple studies to improve cognitive function, including memory (Siervo et al., 2011).

There are at least two mechanisms by which this improvement in memory occurs. The first is at the level of the blood vessels, where vascular function, especially that of delivering oxygenated blood to the brain, improves with weight loss thanks to a reduction in fatty tissues and inflammation. The second is at the level of a person’s metabolism, where the brain is able to better function thanks to modifications in hormone release, such as insulin, after weight loss (Siervo et al., 2011).

Interestingly, weight reduction surgery has also been shown to lead to improved memory. Obese people who underwent bariatric surgery showed long-term improvements on memory tests following their weight-loss-inducing surgeries (Alosco et al., 2014).

But extreme interventions like surgery may not be needed, as nutrition changes by themselves are also associated with positive memory effects, such that eating an appropriate diet can increase cognitive performance (Siervo et al., 2011). Another straightforward ways to improve memory and lose weight at the same time is, of course, regular exercise.

References

Alfaris, N., Wadden, T. A., Sarwer, D. B., Diwald, L., Volger, S., Hong, P., … & Chittams, J. (2015). Effects of a 2‐year behavioral weight loss intervention on sleep and mood in obese individuals treated in primary care practice. Obesity, 23(3), 558–564.

Alosco, M. L., Spitznagel, M. B., Strain, G., Devlin, M., Cohen, R., Paul, R., … & Gunstad, J. (2014). Improved memory function two years after bariatric surgery. Obesity, 22(1), 32–38.

Beccuti, G., & Pannain, S. (2011). Sleep and obesity. Current Opinion in Clinical Nutrition and Metabolic Care, 14(4), 402–412.

Brégeon, D., & Doetsch, P. W. (2011). Transcriptional mutagenesis: Causes and involvement in tumour development. Nature Reviews Cancer, 11(3), 218–227.

O’Brien, K., Venn, B. J., Perry, T., Green, T. J., Aitken, W., & Bradshaw, A. (2007). Reasons for wanting to lose weight: Different strokes for different folks. Eating Behaviors, 8(1), 132–135.

Siervo, M., Arnold, R., Wells, J. C. K., Tagliabue, A., Colantuoni, A., Albanese, E., … & Stephan, B. C. M. (2011). Intentional weight loss in overweight and obese individuals and cognitive function: a systematic review and meta‐analysis. Obesity Reviews, 12(11), 968–983.

Teixeira, P. J., Silva, M. N., Mata, J., Palmeira, A. L., & Markland, D. (2012). Motivation, self-determination, and long-term weight control. International Journal of Behavioral Nutrition and Physical Activity, 9(1), 22.

Vucenik, I., & Stains, J. P. (2012). Obesity and cancer risk: Evidence, mechanisms, and recommendations. Annals of the New York Academy of Sciences, 1271(1), 37.