While you may know that carrying excess weight can negatively impact heart health, do you know why it does? Being overweight or obese can put a direct strain on the heart, which means the heart must work harder to pump blood through a larger body.

Being overweight or obese can also cause elevated blood pressure due to mechanical and hormonal reasons. But being overweight or obese can also affect blood fats, like cholesterol and triglyceride, in ways that can alter your heart health risk.

Cholesterol is a fat-like substance that is made by your body and consumed in the food you eat.

The body uses cholesterol to make hormones, to manufacture vitamin D, and to provide structure for our cells – so cholesterol is very important to health. Cholesterol is transported around the body by lipoproteins, two of which you have probably heard of: HDL (high-density lipoprotein) and LDL (low-density lipoprotein).

HDL is sometimes called the “good cholesterol” because it transports excess cholesterol out of the body so it can’t accumulate in blood vessels. LDL, on the other hand, is referred to as the “bad cholesterol” and is associated with the development of heart disease.

Knowing that excess weight is bad for heart health, most people assume the reason is because excess weight raises LDL levels.

This is actually not true. For the most part, excess weight either does not change LDL levels or only slightly elevates LDL levels. The biggest change seen in LDL levels with weight gain is an increase in the amount of LDL called “small dense LDL.”

This particular form of LDL, which is heavier than other types of cholesterol, is now being scrutinized as a possible marker for the development of plaque in blood vessels.

The most significant adverse impact of increased weight on cholesterol, however, is that it lowers HDL levels.

This is believed to be due to multiple factors, such as the increased uptake of HDL by fat cells and an accelerated breakdown of HDL. Both processes seem to be directly related to the amount of excess weight.

This is important to realize, because very few things raise HDL, so even a small weight loss can significantly benefit HDL levels. A 5-10% weight loss can elevate HDL by five points, resulting in a very favorable decrease in cardiovascular disease risk.

Triglyceride, another form of fat that circulates in your blood, is the main form of fat stored in fat cells. In addition to a low HDL level being present, it is common to find an elevated triglyceride level being present in obesity.

This phenomenon is believed to be caused by two mechanisms – one, an increase in triglyceride secretion into the blood from stored sources, and two, a decreased ability to remove excess triglycerides from the blood.

Similar to what we know about small amounts of weight loss benefiting HDL, a similar 5-10% weight loss can have a big impact on triglyceride levels, such as an average 40-point drop.

When it comes to weight and its impact on blood fats, the relationships are complicated; however, even simple changes in diet and lifestyle can make a big difference.

For most individuals, a 5-10% weight loss is a very achievable goal; for example, a 200-pound person needs only to lose 10-20 pounds. Additional factors that can help include:


References

  1. Klop B, Elte J, Cabezas M. Dyslipidemia in obesity: mechanisms and potential targets. Nutrients 2013;5(4):1218-1240. 
  2. Rashid S, Genest J. Effect of obesity on high-density lipoprotein metabolism. Obesity 2007;15(12):2875-2888.
  3. Taskinen M, Adiels M, Westerbacka J, et al. Dual metabolic defects are required to produce hypertriglyceridemia in obese subjects. Arterioscler Thromb Vasc Biol 2011;31(9):2144-2150.
  4. Singh A, Singh S, Singh N, et al. Obesity and dyslipidemia. Int J Biol Med Res 2011;2(3):824-828.
  5. Kraus W, Houmard J, Duscha B, et al. Effects of the amount and intensity of exercise on plasma lipoproteins. NEJM 2002;347(19):1483-1492.
  6. Liu L, Wang S, Liu J. Fiber consumption and all?cause, cardiovascular, and cancer mortalities: A systematic review and meta?analysis of cohort studies. Mol Nutr Food Res 2015;59(1):139-146.
  7. Li S, Flint A, Pai J, et al. Dietary fiber intake and mortality among survivors of myocardial infarction: prospective cohort study. BMJ 2014;348:g2659. doi: 10.1136/bmj.g2659