Deaths annually
5 million+
attributed to excess weight
Deaths from
1 in 8
non-communicable diseases driven by overweight/obesity
People with
9 in 10
type 2 diabetes have overweight or obesity
Of all cancers
~20%
estimated to involve obesity as a contributing factor
Sources: Blüher 2025, Diabetes Obesity Metabolism [1] · CDC NCHS 2024 [2]
Associated health conditions
These links come from large population studies. A link does not always mean one thing directly causes the other. Many factors contribute to long-term disease.
Type 2 diabetes
Nearly 9 in 10 people with type 2 diabetes have overweight or obesity. Extra fat, especially visceral fat around the organs, drives insulin resistance. That means the body stops responding well to insulin, a core part of how type 2 diabetes develops.
Cardiovascular disease
Obesity increases the risk of high blood pressure (hypertension) by approximately 70%. It also raises LDL cholesterol and triglycerides, and adds to inflammation in the artery walls. All of that feeds into heart attack and stroke risk.
Cancer
Obesity is estimated to contribute to approximately 20% of all cancers. Linked cancers include breast, colorectal, endometrial, oesophageal, kidney, liver, and pancreatic cancers. Colorectal is bowel, endometrial is the womb lining, oesophageal is the gullet.
Obstructive sleep apnoea
Obesity is a leading cause of sleep apnoea in adults. Extra fat around the neck narrows the upper airway during sleep. Breathing stops and starts, over and over.
Fatty liver disease (MASLD)
Extra calories stored in the liver build up as fat (Metabolic dysfunction-Associated Steatotic Liver Disease). It can progress to inflammation, then scarring (fibrosis) and cirrhosis.
Osteoarthritis
Extra weight puts more load on the joints that carry it: hips, knees and ankles. That speeds up the wearing away of cartilage. Fat tissue also releases inflammatory signals (cytokines) that damage joints directly.
Mental health
Obesity is associated with higher rates of depression, anxiety, and social stigma. The link runs both ways. Mental health conditions can also contribute to weight gain.
Excess weight affects nearly every system in the body. But even modest weight loss of 5 to 10 percent can meaningfully reduce many of these risks.
Why even modest weight loss matters
Clinical trials consistently show meaningful health improvements from fairly modest weight loss (5–10%). In a large clinical trial of semaglutide, participants saw significant improvements in blood pressure, cholesterol, blood sugar and CRP, a marker of inflammation. They began well before large amounts of weight were lost. The goal of treatment is not just a lower number on the scale. It is a lower risk of disease.
Common questions
Written and maintained by one person · Built with agentic AI tools · Every number checked against the cited trial · Not medical advice
Key sources for this page
- [1] Blüher M. Obesity — a metabolic disease that deserves attention. Diabetes Obes Metab 2025.
- [2] CDC NCHS Data Brief 508 — Obesity in the United States. 2024.
- [3] Wilding JPH et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1). NEJM 2021.
- [4] Calle EE, Kaaks R. Overweight, obesity and cancer: epidemiological evidence and proposed mechanisms. Nat Rev Cancer 2004.
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