Extensive human evidence strongly supports the conjecture that excess fat tissue is simply harmful. That harm cannot be evaded by exercise: one cannot be "fat but healthy". Visceral fat packed around the abdominal organs generates chronic inflammation, a raised burden of senescent cells, and all sorts of other issues. It pushes fat into the organs themselves; in the case of the pancreas that excess fat is the primary cause of type 2 diabetes. In the liver, it leads to fatty liver disease. Even modest amounts of excess fat tissue raise mortality rates and shorten life expectancy.
A large study finds that physical activity does not undo the negative effects of excess body weight on heart health. "One cannot be 'fat but healthy'. This was the first nationwide analysis to show that being regularly active is not likely to eliminate the detrimental health effects of excess body fat. Our findings refute the notion that a physically active lifestyle can completely negate the deleterious effects of overweight and obesity."
The study used data from 527,662 working adults insured by a large occupational risk prevention company in Spain. The average age of participants was 42 years and 32% were women. Participants were categorised as normal weight, overweight, or obese. Additionally, they were grouped by activity level: 1) regularly active, defined as doing the minimum recommended for adults by the World Health Organization (WHO); 2) insufficiently active, some moderate to vigorous physical activity every week but less than the WHO minimum; 3) inactive. Cardiovascular health was determined according to three major risk factors for heart attack and stroke, namely diabetes, high cholesterol, and high blood pressure.
Approximately 42% of participants were normal weight, 41% were overweight, and 18% were obese. The majority were inactive (63.5%), while 12.3% were insufficiently active, and 24.2% were regularly active. Some 30% had high cholesterol, 15% had high blood pressure, and 3% had diabetes. The researchers investigated the associations between each weight category and activity group and the three risk factors. At all weight levels, any activity (whether it met the WHO minimum or not) was linked with a lower likelihood of diabetes, high blood pressure, or high cholesterol compared to no exercise at all. At all weights, the odds of diabetes and hypertension decreased as physical activity rose.
However, overweight and obese participants were at greater cardiovascular risk than their peers with normal weight, irrespective of activity levels. As an example, compared to inactive normal weight individuals, active obese people were approximately twice as likely to have high cholesterol, four times more likely to have diabetes, and five times more likely to have high blood pressure. "Exercise does not seem to compensate for the negative effects of excess weight. This finding was also observed overall in both men and women when they were analysed separately."