How to prevent obesity?

Definition and causes of overweight/obesity

Since 1975, the number of people experiencing obesity has tripled. The World Health Organization (WHO) defines overweight and obesity as abnormal and excessive accumulation of body fat that poses a health risk.

Obesity is a chronic disease and therefore needs to be diagnosed and treated. It should also be noted that it is not a metabolic disease but a result of nutrition disturbances, insufficient physical activity and the resulting positive energy balance. The WHO diagnostic criterion is the BMI parameter calculated by dividing body weight (in kg) by the square of body height (expressed in metres). A value above 30kg/m2 is considered grade I obesity, and values above 25kg/m2 are diagnosed as overweight.

Risk factors for the development of obesity include lifestyle, availability of energy-dense foods, psychological factors (e.g. anxiety disorders or ‘stress eating’) or hormonal factors (e.g. hypothyroidism, Cushing’s syndrome, Down syndrome).

Complications of overweight/obesity

Overweight and obesity may cause of many complications, including disturbances in the secretion of cytokines produced by adipose tissue (adipokines), the development of insulin resistance, hyperinsulinemia or accumulation of fat outside adipose tissue (e.g. in the liver). As the disease progresses, it contributes to the development of type 2 diabetes, dyslipidaemia, a number of cardiovascular diseases (e.g. hypertension, atherosclerosis), endocrine disorders, as well as cancer. Obesity is also accompanied by other health problems related to fat accumulation, e.g.: gastro-oesophageal reflux, sleep apnoea, lung ventilation disorders, mobility problems resulting from osteoarthritis, gallstones and the general deterioration of life quality.

Prevention of obesity

Reducing body weight leads to an overall health improvement (e.g. it reduces blood glucose, glycated haemoglobin, LDL cholesterol ratio and triglycerides) and a lower risk of developing type 2 diabetes or cardiovascular diseases. It may result in a smaller intake of blood pressure or glucose-lowering drugs and an overall life quality improvement.

Given the proportion of the population that is overweight/obese, prevention is extremely important. As part of primary prevention, it is recommended to eat a balanced and varied diet according to individual energy requirements. According to the recommendations, 20-35% of the daily energy requirements should be satisfied by fats (a higher percentage of fat in the diet for more physically active people), obviously taking into account their quality. In practice, this means limiting the intake of products containing saturated fatty acids (e.g. sweet/salty snacks/products made using palm fat or butter, which also contain trans fats, chocolate, etc.) and increasing the intake of products rich in mono- (e.g. olive oil) and polyunsaturated fatty acids (fish, some seaweeds). Carbohydrates should account for 55-75% of the calories consumed (but the intake of simple carbohydrates, i.e. glucose, fructose, lactose and sucrose should be limited). Proteins should complete the energy value of the diet (10-15%). Dietary fibre in the amount from 18 g to 38 g per day must be a fixed component of the diet.

One diet that has recently gained many followers is Intermittent Fasting (IF), which is based on periods of fasting and dietary restrictions resulting in significant calorie restrictions alternated with periods of eating without restrictions. Its main feature is the abandonment of traditional meal intervals. The most common variant is the 16/8 regime, i.e. 16 hours of fasting and an 8-hour eating window. There is scientific data reporting that this type of diet has beneficial effects for weight reduction in adults. A new systematic review, published in 2020, analysed IF in the context of obesity treatment and included a total of 18 randomised trials (studies in which participants are randomly assigned to a drug/intervention or placebo group) with a control group and 9 studies without a control group. These studies lasted between 2 and 26 weeks and included between 10 and 244 participants. Only 2 studies covered the period of one year. All studies reported weight loss ranging from 0.8% to 13%, relative to the weight recorded at the start of the study. No serious side effects were reported. In 12 studies comparing IF with calorie restriction no differences between the two approaches were reported. Studies including patients with type 2 diabetes reported improved glycaemic control. The main limitation of the studies presented was a small number of participants and a short follow-up period.

Diet in combination with adequate physical activity should become a part of lifestyle. Due to the early formation of eating habits that may later burden a person’s adult life, it is recommended that health concerns regarding diet and physical activity be part of a health-promoting education from an early age.

Reference literature:

1. www.who.int/topics/obesity/en (dostęp 29.06.2021)
2. Conus F., Allison D.B., Raabasa-Lhoret R. i wsp.: Metabolic and behavioral characteristics of metabolically obese but normal weight women. J. Clin. Endocrinol. Metabol., 2004; 89: 5013–5020
3. Endalifer, M. L., & Diress, G. (2020). Epidemiology, predisposing factors, biomarkers, and prevention mechanism of obesity: A systematic review. Journal of obesity, 2020.
4. Long, J. D., Dodd, S. L., Doumit, R., Boswell, C., O’Boyle, M. W., & Rogers, T. (2020). Integrative Review of Dietary Choice Revealed by fMRI: Considerations for Obesity Prevention and Weight‐Loss Education. Worldviews on Evidence‐Based Nursing, 17(2), 151-157.
5. https://www.pzh.gov.pl/wp-content/uploads/2020/12/Normy_zywienia_2020web-1.pdf (dostęp 29.06.2021)
6. Welton, S., Minty, R., O’Driscoll, T., Willms, H., Poirier, D., Madden, S., & Kelly, L. (2020). Intermittent fasting and weight loss: Systematic review. Canadian Family Physician, 66(2), 117-125.
7. https://www.mp.pl/pacjent/dieta/diety/diety_alternatywne/63644,diety-alternatywne (dostęp 29.06.2021)

About the author

Joanna Zając, PhD, has been working as a teacher and researcher at the Department of Hygiene and Dietetics of the Jagiellonian University Medical College for 12 years. She is a member of the Polish Cochrane Branch (an organisation of independent researchers, specialists and patients aiming to develop reliable and accessible information about health) and a co-author of systematic reviews. Her research interests focus on dietetics and the methodology of studies.