Overnutrition occurs when an individual consistently consumes more nutrients, particularly calories, than their body requires for normal functions, growth, and metabolism. This excess energy intake leads to the storage of surplus energy, primarily as body fat. Overnutrition in modern society contributes to a broad spectrum of health consequences, impacting various bodily systems.
Metabolic and Cardiovascular Conditions
Overnutrition contributes to the development of insulin resistance, a condition where the body’s cells do not respond effectively to insulin. Enlarged fat cells can trigger chronic inflammation, which impairs insulin signaling. This impaired response necessitates the pancreas to produce more insulin, eventually leading to elevated blood sugar levels and often progressing to Type 2 Diabetes.
The accumulation of excess body fat, particularly around the abdomen, is a factor in the development of metabolic syndrome. This syndrome is a cluster of risk factors including high blood glucose, unhealthy cholesterol levels (low “good” HDL cholesterol and high triglycerides), and high blood pressure (hypertension). Having three or more of these conditions increases the likelihood of developing cardiovascular disease and Type 2 Diabetes.
Overnutrition also promotes atherosclerosis, a process where fatty deposits, or plaque, build up inside arteries. This buildup narrows the arteries, making it harder for blood to flow and increasing the risk of heart disease and stroke. The chronic low-grade inflammation and oxidative stress associated with overnutrition contribute to endothelial dysfunction, impairing the blood vessels’ ability to relax and constrict properly. These combined effects heighten the risk of cardiovascular events, including heart attacks and strokes.
Liver and Kidney Complications
Overnutrition drives Non-Alcoholic Fatty Liver Disease (NAFLD), a condition characterized by excessive fat accumulation in the liver not caused by alcohol consumption. This initial stage, simple steatosis, can progress to Non-Alcoholic Steatohepatitis (NASH), where liver fat is accompanied by inflammation and liver cell damage. NASH can lead to fibrosis, the formation of scar tissue, and eventually cirrhosis, which impairs liver function and can result in liver failure.
The mechanisms linking overnutrition to NAFLD and its progression involve increased circulating free fatty acids, which the liver takes up excessively. This overload impairs insulin signaling within liver cells and promotes de novo lipogenesis, the creation of new fats, leading to fat accumulation. Chronic inflammation and oxidative stress within the liver also contribute to the progression from simple steatosis to more severe forms of liver injury.
Overnutrition also contributes to chronic kidney disease (CKD) through several pathways. The metabolic disorders often associated with overnutrition, such as hypertension, dyslipidemia, and diabetes, amplify renal dysfunction. Excess body fat can lead to intrarenal fat accumulation, particularly around the kidney capsule, and cause hemodynamic changes, including increased renal blood flow and hyperfiltration, which put an increased workload on the kidneys. Insulin resistance and systemic inflammation, common in overnutrition, are closely linked to renal inflammation and fibrosis, accelerating CKD progression.
Increased Cancer and Joint Disease Risk
Overnutrition is recognized as a risk factor for several types of cancer. Studies show an association with increased risk for cancers of the esophagus (adenocarcinoma), colon, pancreas, post-menopausal breast, endometrium, kidney, and liver. For instance, an increase in Body Mass Index (BMI) is associated with a higher risk for esophageal adenocarcinoma and endometrial cancer.
Proposed mechanisms linking overnutrition to cancer risk include chronic low-grade inflammation, which can promote cell proliferation and survival, and altered hormone levels, such as increased estrogen in post-menopausal women, which influences breast and endometrial cancer risk. Insulin resistance and increased levels of insulin-like growth factors can also stimulate cancer cell growth.
Excess body weight places mechanical strain on weight-bearing joints, such as the knees and hips, contributing to the development and worsening of osteoarthritis. This mechanical stress accelerates the degradation of articular cartilage, the smooth tissue covering the ends of bones. The link between overnutrition and osteoarthritis extends beyond mechanical stress, as adipose tissue, particularly abdominal fat, releases pro-inflammatory cytokines, known as adipokines, into the bloodstream. These systemic inflammatory mediators can contribute to a low-grade inflammatory state, affecting joint tissues even in non-weight-bearing joints like the hands.
Other Systemic Health Impacts
Overnutrition is associated with obstructive sleep apnea (OSA), a condition where breathing repeatedly stops or becomes very shallow during sleep. The excess fat deposition around the upper airway, including the tongue and pharyngeal walls, can reduce the airway’s cross-sectional area, making it more prone to collapse during sleep when muscles relax. This obstruction leads to drops in oxygen levels and disrupted sleep, which can impact appetite-regulating hormones like leptin and ghrelin, potentially contributing to a cycle of weight gain and worsening OSA.
Overnutrition also has implications for mental health, with a bidirectional relationship between excess weight and conditions such as depression and anxiety. Physiological factors include chronic inflammation and altered neurotransmitter pathways, which can affect mood regulation. Psychologically, societal stigma, body image dissatisfaction, and low self-esteem can contribute to or exacerbate feelings of depression and anxiety. Many individuals may engage in emotional eating as a coping mechanism for stress or negative emotions, perpetuating the cycle of overnutrition.
Reproductive health can also be impacted by overnutrition in both men and women. In women, excess body fat can lead to hormonal imbalances, affecting ovulation and increasing the risk of conditions like polycystic ovary syndrome (PCOS), a common cause of infertility. In men, overnutrition, particularly obesity, has been linked to compromised sperm quality. These effects can contribute to subfertility or infertility and influence offspring health outcomes.