A high BMI when you’re young increases the risk of heart failure, even if you’re dieting away the pounds as you get older. Yo-yo dieting is the worst.
HEART FAILURE: It comes down to starting healthy habits early. Fortunately, it’s never too late to adopt a healthier lifestyle, and losing weight is great for reducing your risk of heart attack. But you can still be at a higher risk for other heart problems if you’re late in changing your habits.
How dangerous is it?
- RISK OF HEART ATTACK: Even when taking into account differences in age, smoking, socioeconomic factors and physical activity level, people who were slightly overweight for 30 years (average BMI of 25 to 27.5) had a 17 per cent greater risk of heart attack as compared with those in the normal weight range and with average BMI (18.5 to 25).
- Individuals who were morbidly obese for 30 years (average BMI over 35) had a 66 per cent increased risk.
- RISK OF HEART FAILURE: The risk of heart failure increased by 45 percent in slightly overweight individuals, was approximately double in those with persistent obesity (BMI 30-35), and was about four times greater when the average BMI was higher than 35 for 30 years.
- Unlike heart attack risk, it played no significant role for heart failure risk if the most recent BMI measurement was lower than the first two.
Excessive weight at a young age puts one at a far higher risk of heart failure as compared with maintaining a healthy weight throughout one’s life. Even slight overweight increases risk by 45 per cent as compared with normal weight. (See fact box.)
Researchers fear that the obesity epidemic will lead to more cases of heart failure even if younger people with obesity are able to adjust their weight later in life.
“If the current trend continues, 60 per cent of the world’s population will have a BMI in the overweight or obese range by 2030,” says NTNU professor Imre Janszky of the Department of Public Health and General Practice.
Especially worrisome is the increasing incidence of obesity in children, he says.
“Since our study results suggest that obesity is a major risk factor for both heart attacks and heart failure, the obesity epidemic has considerable significance for the scope of these diseases,” says Janszky.
- You might also like: A few extra kilos aren’t so good for you after all
Average BMI is most important
Between 1966 and 1969, residents in Nord-Trøndelag were weighed and measured in conjunction with a mass tuberculosis screening.
More than 26,000 of the same individuals also participated in both the second and third Nord-Trøndelag Health Studies (HUNT) in the mid-1980s and mid-1990s.
Whereas a person’s most recently measured BMI value was the one most strongly associated with the risk of getting a heart attack, the risk of heart failure, by contrast, corresponded more strongly with a person’s average BMI over a period of 30 years.
The study, recently published in the Journal of Internal Medicine, revealed that a high BMI earlier in life increased the risk of heart failure even when researchers adjusted the analysis for the most recent BMI measurement.
“The findings indicate that persistent obesity affects the heart over time, and that BMI in early life is an important factor that can increase the risk of heart failure in middle age,” says Janszky.
For heart attacks, however, the most recent BMI measurement was the most important factor, which may indicate that it is never too late to lose weight if you want to reduce your risk of acute myocardial infarction.
HUNT study statistics
By the end of 2008, 1851 of the 26,000 Norwegians in the HUNT Study had experienced a heart attack, and 946 had heart failure. Higher BMI was associated with an increased risk of both heart attack and heart failure, and obesity was associated with a particularly high risk for heart failure.
The risk increased even after the researchers had adjusted the analyses for gender, age, smoking, alcohol consumption, education level, marital status and physical activity.
“When we then also adjusted for metabolic status, the relationship between BMI and heart attack was no longer significant, which indicates that the metabolic consequences of overweight and obesity appear to have the greatest impact for heart attacks,” says Janszky.
Heart failure and heart attack
HEART FAILURE occurs when the heart is not able to pump blood around the body strongly enough for all organs to receive an adequate blood supply. The most typical symptoms are shortness of breath and impaired physical performance, and eventually leg swelling may develop.
Between 100,000 and 200,000 Norwegians are estimated to be living with heart failure. Many have no idea that they even have it. Half of them die within five years of their diagnosis, making heart failure more deadly than most cancers.
HEART ATTACKS occur when a blood clot blocks one of the coronary arteries, preventing the supply of blood and oxygen to part of the heart. The heart is damaged after a few minutes, and if the blood supply is cut off for a longer time, the part of the heart not getting blood dies. The dead tissue creates the actual attack.
A total of 115,000 Norwegians—or approximately 13,000 new cases each year—were hospitalized with their first heart attack between 2001 and 2009.
In plain speak, this means that a high BMI is not the direct cause of a heart attack, but that overweight and obesity increase the risk of high blood pressure, high blood sugar and an unfavourable blood fat profile, which in turn increase the risk of heart attack.
These factors, however, could not explain the correlation between high BMI and heart failure, which may indicate that obesity itself weakens the heart.
- You might also like: Call them spare tires or love handles—belly fat is bad
Stable weight may be best
The researchers also examined how changes in body weight over time were associated with future heart failure. Study results showed that weight loss and weight gain were both associated with increased risk.
Those who maintained a stable weight throughout all three measurement periods had a lower risk than those whose weight fluctuated.
“There was a particularly strong increase in risk for people whose mid-1980s BMI varied from their other two measurements. This may indicate that yo-yo dieting involves additional risks,” says Janszky, although he stresses that this interpretation is just based on a single BMI measurement between the first and last measurements.
Reference: Janszky, I., Romundstad, P., Laugsand, L. E., Vatten, L. J., Mukamal, K. J., & Mørkedal, B. (2016).Weight and weight change and risk of acute myocardial infarction and heart failure–the HUNT Study. Journal of Internal MedicinePublished 5 April 2016 (online).