Cracking the Vault: Slow over Fast Meals
Intermittent fasting has been gaining popularity as a weight loss method over the past few years. I never thought cramming all your calories for the day in 8 hours was such a good idea and now research has backed me up. An observational study by the American Heart Association found that this time-restricted eating (TRE) method may not be so great for your heart.
The observational study included over 20,000 US adults and found that people who consumed most of their meals in under an 8-hour window had the highest risk for cardiovascular deaths compared to people who ate meals in a typical 12 to 16-hour day. Cardiovascular mortality was seen in those with or without cardiovascular disease or cancer.
“These findings require replication and we cannot demonstrate 8-hour TRE causes cardiovascular death in this observational study," notes Victor Wenze Zhong, PhD, the lead study author.
Zhong, professor and chair of the Department of Epidemiology and Biostatistics, School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China also states that patients, especially those that have cancer or existing heart conditions, should be aware of the link between the risk of cardiovascular death when using an 8-hour feeding window.
Scary Results
Short-term studies of 8-hour time-restricted eating (TRE) find that it may help improve some cardiometabolic risks like high blood sugar. But, the long-term effect of TRE is unknown.
Professor of Medicine at Stanford University in California, Christopher Gardener, PhD claims that despite the short-term benefits of TRE, long-term effects should be studied more.
The study included diet patterns in over 20,000 subjects who were part of the 2003-2018 National Health and Nutrition Examination Surveys (NHANES). During the initial enrollment year, all subjects provided two 24-hour diet recalls. The National Death Index was used to determine deaths through the end of 2019.
Deaths that occurred from any cause were 2797 in the average follow-up of 8 years while 840 were related to cardiovascular disease and 643 were from cancer.
Subjects using an 8-hour feeding window had a significantly higher risk of cardiovascular mortality compared with those with eating patterns that were typically 12 to 16 hours. This association was also seen in those with cardiovascular disease and cancer. This connection was also observed in subjects with cardiovascular disease who had a feeding window of 8 to under 10 hours each day.
Significant links were not observed in eating duration and all-cause or cancer deaths in the overall sample and CVD/cancer sub-samples with the exception that an eating window of over 16 hours was linked with a lower risk for cancer deaths in those with cancer.
Quality Above All
Zhong states it’s unclear what the underlying connection is between 8-hour TRE and cardiovascular death. He did note that subjects who limited eating to a period less than 8 hours per day had less lean muscle mass than people with usual eating patterns of 12-16 hours. A higher risk of cardiovascular mortality has been associated with loss of lean muscle mass.
He also states that for now, putting more focus on the quality of a person’s diet is more important than the time restriction. The DASH and Mediterranean diets have well-researched health benefits according to Zhong.
Sean Heffron, MD, a cardiologist at the Center for the Prevention of Cardiovascular Disease at NYU Langone Heart, New York, NY, who wasn't involved in the study states, “Intermittent fasting is certainly an interesting concept and one on which the potential mechanisms underlying the improvements in short outcome studies and preclinical studies in animals are strongly being pursued."
Heffron is skeptical about the results since the data was based on 2-day diet histories without considering confounding variables. He commented that the restricted group had more smokers and more males. "I would strongly anticipate that once appropriate corrections are made, the findings will no longer persist in statistical significance," Heffron said.
He stressed the importance of more rigorous studies before making diet recommendations. If patients ask about fasting, he advises them “If it works for you, that's fine," but he doesn't provide a recommendation for or against it.
Tips to lose weight AND protect your heart:
Eat balanced, calorie-controlled meals including lean protein, healthy fats, and high-fiber carbs. Make dinner your smallest meal and spread calories out throughout the day.
Rather than TRE, stop snacking after dinner and at least 3-4 hours before bedtime.
Drink water over soda, juice, alcohol, or other high-calorie beverages.
Get at least 7 to 8 hours of sleep per night.
Include lots of fruits and vegetables in your diet and moderate portions of whole grains.
Eat less red meat, processed meat, and pork. Add beans or lentils to your diet 3 x per week.
Include fish in your diet twice per week and cook it in a healthy manner (grilled, baked, air-fried).
Do regular cardio exercises 30 to 45 minutes per day at least 5 days/week.
Include 2 days of strength training exercises to build and maintain lean muscle mass.
Meet with a Registered Dietitian to provide a heart-healthy meal plan for you!
Lisa Andrews, MEd, RD, LD
Intermittent Fasting Linked to Higher CVD Death Risk - Medscape - March 19, 2024.