5 Major Effects of Obesity on Your Health
Obesity is a largely preventable condition that is one of the leading causes of early death and is a primary risk factor for several chronic diseases, including type 2 diabetes, cancer, heart disease, and dementia. The excess weight that is characteristic of obesity also increases inflammation and stress on the body’s organs and cells, leading to premature aging.
This article will dive into the top five deleterious effects of obesity on health outcomes, as well as outline important steps you can take to reach a healthier weight, which can mitigate the effects of obesity and potentially lead to increased lifespan (the years lived) and healthspan (the years lived healthfully).
The Stats on Obesity
The prevalence of obesity has been steadily increasing over the last few decades, in both the United States and worldwide. According to the Centers for Disease Control and Prevention (CDC), obesity rates reached 42.8% of American adults in 2018.
Obesity is defined by the body mass index (BMI), which is a weight-for-height ratio. An overweight BMI is between 25.0 and 29.9 kg/m2, while obesity is classified by a BMI above 30 kg/m2, and severe obesity is above 40 kg/m2. From the CDC data, the highest prevalence of severe obesity was found in adults aged 40-59 and non-Hispanic African Americans.
Globally, obesity rates have tripled since 1975. According to the World Health Organization (WHO), over 650 million adults were classified as obese in 2016 worldwide.
The Five Effects of Obesity on Health
The health conditions that are impacted by obesity are wide-reaching. From cancer to cardiovascular disease to cognitive decline, having a BMI over 30 puts you at an increased risk of developing a chronic disease (or several).
1. Type 2 Diabetes
Commonly referred to as “diabesity,” type 2 diabetes and obesity tend to go hand-in-hand. As it affects about 10% of American adults, the prevalence of diabetes has steadily been rising alongside obesity. If these trends continue, it’s estimated that one in three Americans will have diabetes by the year 2050.
Obesity is a cause of diabetes because the increase in fatty tissue leads to cells becoming more insulin resistant, which is a hallmark of developing the disease. In a large, November 2018 meta-analysis published in JAMA Network Open that included almost one million people, each one-point increase in BMI increased the odds of type 2 diabetes by 67%.
In epidemiological research, rates of diabetes have increased the most in those who were obese. Currently, over 85% of people with type 2 diabetes are obese. Diabetes is the seventh leading of cause of death worldwide and leads to several major complications if uncontrolled, including:
- Retinopathy: Damage to the blood vessels of the eyes, which leads to vision problems and blindness.
- Nephropathy: Damage and disease of the kidneys, which leads to end-stage renal disease if untreated.
Neuropathy: Damage to the peripheral nerves, which leads to tingling and loss of feeling in extremities, and eventually amputations if untreated.
Obesity may be a driver for both the development and progression of various cancers. It’s been estimated that 14% of deaths from cancer in men and 20% in women can be attributed to obesity, as reported in a prospective cohort of over 900,000 Americans.
The increase in caloric intake and fat deposits that are seen with obesity can trigger metabolic changes that may increase carcinogenesis, with some tissues being more affected by others. Obesity can increase inflammatory signaling molecules, like the cytokines TNF, IL-6, and IL-1β, which may be involved with cancer growth.
A meta-analysis published in the International Journal of Cancer in October 2018 reviewed data from over 1.5 million individuals. They found the strongest positive associations between increased BMI and endometrial cancer, esophageal adenocarcinoma, and kidney cancer, as well as a strong male-specific link between obesity and colorectal cancer. Of the 23 total cancer types studied, 18 were positively associated with increased BMI.
Although obesity and cancer are both complex diseases without just one single cause, it does appear that a higher BMI may be a strong risk factor for developing various types of cancers.
3. Heart Disease and Hypertension
The effects of obesity are seen in various cardiovascular-related diseases, which include coronary heart disease, stroke, hypertension, and heart failure, amongst others. Obesity is often accompanied by other metabolic conditions, including dyslipidemia and insulin resistance, which are all risk factors for cardiovascular diseases.
Even in people who were found to be “metabolically healthy,” being overweight or obese was still an independent risk factor for developing coronary heart disease (CHD) in the 2018 European Prospective Investigation into Cancer and Nutrition study, which looked at 520,000 individuals over a 12-year period.
In a 2014 study published in Lancet, each 5 kg/m2 BMI increase was associated with a 27% increase in CHD and an 18% increase in stroke, when adjusted for age, sex, and smoking status. When further adjusted for metabolic confounders (like blood pressure and cholesterol), the strength of the association decreased but was still linked to a 15% increase in CHD and a 4% increase in stroke, with the most important mediating confounder being high blood pressure.
Obesity is an important risk factor for high blood pressure, or hypertension, as the combination of the two can lead to kidney and heart disease. Not only that, but being obese increases the chances that someone will be resistant to hypertension treatment. It also appears to be a cyclical process, in that hypertensive patients are more likely to gain weight, so high blood pressure is a risk factor for obesity and vice versa.
4. Alzheimer’s Disease and Dementia
The relationship between cognitive decline and obesity is especially important as we consider that the rates of Alzheimer’s disease are expected to triple within the next 30 years. The first signs of dementia can be found in the brain approximately 20 years before symptoms arise, thus it’s crucial to take preventive measures to reduce your risk as you age.
The strongest association between obesity and dementia occurs when an individual is obese at mid-life, as a June 2015 review published in Alzheimer’s & Dementia has concluded.
A 28-year follow-up study confirmed that conclusion. Published in Alzheimer’s & Dementia in February 2018, the Whitehall II Study followed over 10,000 adults and found that obesity at age 50, but not at age 60 or 70, was linked to an increased risk of dementia. The researchers hypothesize that the link between obesity and dementia decreases with age due to the long period between preclinical brain changes and time of diagnosis; those with dementia tend to lose weight up to 10 years prior to having symptoms of cognitive impairment, for reasons ranging from increased apathy to changes in appetite.
5. Premature Aging
Aging and obesity share many similar factors, including increased inflammatory markers, impaired immunity, and compromised mitochondrial function. Obesity is a risk factor for lowered life expectancy, as being obese has been shown to reduce lifespan by 5.8 years in men and 7.1 years in women.
Obesity increases the risk of telomere shortening; telomeres are the endcaps of chromosomes that are markers of biological age and are shortened during the aging process. A meta-analysis of 63 studies published in Obesity in 2015 found that there was a negative correlation between obesity and telomere length, meaning that an increase in obesity was linked to a reduction in telomere length.
Levels of NAD+, which is a coenzyme needed for metabolism and DNA repair, declines both during aging and in people with obesity. Thus, obesity may accelerate the aging process by further reducing NAD+ levels.
Lastly, obesity can interfere with autophagy, which is our body’s way of recycling dysfunctional or damaged cells. A reduction in autophagy is linked to increased cellular aging and disease, providing yet another reason as to how obesity can play a role in premature aging.
Tips to Lose Weight or Prevent Obesity
Although obesity is a multifactorial and complex condition, there are several things you can do to improve your health by maintaining a healthy weight.
Regular physical activity is a big contributor to maintaining a healthy weight, as well as reducing the risk of chronic disease. If you’re not used to exercising, start off slowly by walking. Even walking for 20 minutes per day can reduce the risk of obesity.
Reduce Processed Foods and Added Sugar
Added sugar and refined carbohydrates in processed foods make up a large proportion of the calories that the typical American eats. Replace packaged and processed foods with whole foods (that only have one or two ingredients) to increase weight loss.
Watch out for added sugar in obvious things, like juice and soda, but also in foods like salad dressings, pasta sauces, and condiments. Cooking more at home, rather than eating take-out or at restaurants, can also decrease your caloric intake and improve your health.
Eat More Plants
Vegetables and fruits contain antioxidants, vitamins, and minerals, as well as dietary fiber, which can increase satiety and benefit your gut microbiome. During a 12-year follow-up study, women who increased their vegetable intake from about three daily servings to five daily servings had a 25% reduced risk of becoming obese, compared to those who reduced their vegetable intake.
- The effects of obesity are wide-reaching, and rates of obesity are increasing year after year.
- The top chronic diseases that are impacted by obesity are type 2 diabetes, cancer, cardiovascular disease, and dementia, as well as accelerated rates of aging.
Reduce your risk of becoming obese by exercising and moving more, eating more vegetables, cooking at home more often, and reducing your intake of added sugars and processed food.
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