The Nutrition Examination Research Digest (NERD) aims to provide rigorous, unbiased analysis of the latest and most important nutrition and supplementation studies. Click here to subscribe or login if already a subscriber .
Study under review: Weight Loss and Serum Lipids in Overweight and Obese Adults: A Systematic Review and Meta-Analysis
Introduction
Obesity is associated with an unfavorable blood lipid profile, with approximately 60–70% of people with obesity being classified as dyslipidemic[1], meaning they have unhealthy levels of fats circulating in the bloodstream. In particular, excess visceral abdominal tissue[2], or fat surrounding the abdominal organs, is accompanied by elevated triglycerides (TG) and low-density lipoproteins (LDL), and reduced high-density lipoproteins (HDL), which promotes the formation of fatty plaques in the arteries. The unfavorable blood lipid profile observed in many people with obesity is thought to increase the risk of cardiovascular disease.
Losing weight has been promoted as a way to improve lipid profile[3] for people with overweight and obesity[4]. An improved lipid profile is characterized by lower total cholesterol (TC), TG, and LDL, and increased HDL. In 2013, the [5]American College of Cardiology / American Heart Association (ACC/AHA[5]) stated that there was a dose-response relationship between weight loss and improvement in lipid profile. In 2019, the ACC/AHA stated that an elevated blood cholesterol level is a major cardiovascular disease risk factor and recommended weight loss as a way to decrease risk of cardiovascular disease.
Although there is evidence to suggest that weight reduction significantly reduces[3] TC, LDL cholesterol, and TG levels, and increases HDL cholesterol in people with overweight, it is not clear how much weight loss is required to observe changes in these lipid parameters, what measures used to achieve weight loss are most effective, or how long it takes to experience an improvement in lipid profile.
To help clarify these issues, the Endocrine Society wanted to develop guidelines for the management of lipids in the context of endocrine disorders. The authors of this study were charged with helping develop the guidelines, which spurred them to conduct this systematic literature review and a meta-analysis to evaluate the magnitude of changes in lipid parameters in people with obesity. The authors also explored whether the used method of weight loss resulted in any difference by evaluating the association of lipid levels with weight lost via lifestyle changes (diet and/or exercise), pharmacotherapy (weight loss drugs), or bariatric surgery.
Alterations in lipid metabolism, called dyslipidemia, are relatively common in people with obesity, and weight loss can significantly improve their lipid profile. However, it’s unclear how much blood lipids change as weight is lost, and whether the weight loss method affects how blood lipids change. Researchers conducted the study under review to help the Endocrine Society develop guidelines for lipid management in endocrine disorders.
What was studied?
What were the findings?
The bigger picture
Frequently asked questions
What should I know?
Other Articles in Issue #74 (December 2020)
-
Deep Dive: Comparing different protein sources' impact on bone turnover
Eating more plants can be healthy but may negatively impact bone health due to lower protein, calcium, and vitamin D intake. This trial examined how the same amount of protein from animal or plant sources affected bone turnover.
-
Deep Dive: Does low protein intake slow down chronic kidney disease progression?
Very low protein diets seem to slow progression but don't affect mortality, raising the question of whether there's a risk-benefit tradeoff. Higher quality, larger trials could shed more light on this issue.
-
Deep Dive: How does alternate-day fasting compare to no diet or other diets?
ADF helps people lose weight and lower cholesterol, but there's no clear advantage over continuous energy restriction based on the current evidence. Larger, longer studies are needed, though.
-
NERD Mini: Dietary approaches and supplements to combat chronic pain
What nutritional interventions impact different chronic pain conditions? This NERD Mini summarizes the evidence from a systematic review released earlier this year.
-
Interview: Jeff Rothschild, RD, CSSD, PhD(c)
What should we eat before exercise? To find out, we picked the lead author's brain of a recent review that answers that exact question!
-
Deep Dive: Will nitrates improve your training performance? It depends!
Nitrates provide a small but significant performance boost, but dose, timing, and your baseline aerobic fitness matters.
-
Deep Dive: The best non-drug ways to lower blood pressure
Drugs are usually an effective way to lower blood pressure, but non-drug interventions can help a lot, too! This network meta-analysis looked at which non-drug methods are the best for lowering blood pressure.
