Fitness might not mitigate the negative effects of excess body weight on heart health, according to a new study that found being regularly active is not likely to eliminate the detrimental health effects of increased body fat.

The findings were published in the European Journal of Preventive Cardiology and 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 (BMI 20.0–24.9 kg/m2), overweight (BMI 25.0–29.9 kg/m2), or obese (BMI 30.0 kg/m2 or above). Additionally, they were grouped by activity level:

  • Regularly active, defined as doing the minimum recommended for adults by the World Health Organization
  • Insufficiently active (some moderate to vigorous physical activity every week but less than the WHO minimum)
  • Inactive (no exercise).

Cardiovascular health was determined according to three major risk factors for heart attack and stroke, namely diabetes, high cholesterol, and high blood pressure.

One cannot be 'fat but healthy'

The researchers investigated the associations between each BMI and activity group and the three risk factors. At all BMI 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 also 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. 

For 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. 

Study author Dr Alejandro Lucia of the European University, Madrid, Spain, said: “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.

Fighting obesity and inactivity is equally important; it should be a joint battle. Weight loss should remain a primary target for health policies together with promoting active lifestyles.”