In the Know
Science says diet and exercise are keys to a healthy life. But Dr. Dorothy Sears, as a guest of the Howell Foundation, offered two ways to adjust diet and exercise habits for long-lasting improvements to well-being. At a luncheon lecture May 20 at La Jolla Country Club, the Associate Professor of Medicine, Division of Endocrinology and Metabolism at UC San Diego, shared her research, the data it yielded, and her “lifestyle interventions.”
The take-aways: it’s not what you eat, but when you eat it; and sit less.
An advocate for lifestyle changes to supplement (or in some cases to replace) traditional medications, Sears explained that in a study of those with “pre-diabetes” (starting to experience metabolic problems or with diabetes in their family), researchers looked at the effectiveness of a drug intervention compared to lifestyle changes. The data suggested that a moderate diet modification — such as eating more fruits and vegetables, walking more, etc. — was associated with a 58 percent reduction in incidences of Type II Diabetes. Those who used medication saw a reduced risk of 38 percent.
“So in this battle, lifestyle modification won,” she said.
A ‘fast’ way to health
Sears is studying the effectiveness of intermittent fasting, particularly for long periods at night, using biological markers for certain cancers, cardiovascular disease and diabetes. “We studied large populations and found that those who eat during the night have increased risk of chronic disease,” she said. “We hear a lot about what’s healthy to eat — eat this, don’t eat that, count calories, look at nutrition labels — but what if you could eat whatever you wanted, just so long as it was at a certain time that you ate it?”
Intermittent fasting, she explained, can mean fasting for one whole day per week; increasing the hours of not eating between dinner at night and breakfast the next morning; or engaging in a fast called the 5-2, where participants eat whatever you want for five days and then for two non-consecutive days participants only eat 500 calories.
Focusing on “time-restricted” eating (only eating for certain hours during the day) Sears studied how the practice affected both mice and women.
“In mice, we found the length of that nightly fasting period impacts health and is associated with better glucose control and decreased inflammation,” she said. In humans, “We looked at more than 2,500 women and we found that every three-hour increase in this fasting period of time during the night, yielded a reduced risk of having an elevated hemoglobin A1C (a marker of high glucose in the blood). So the longer the nighttime fasting, the lower the A1C.”
In a similar study of breast cancer survivors, which Sears said was “the first time a human study has been able to demonstrate clinical outcome of cancer recurrence,” researchers looked at 2,300 women over seven years.
“We know who got breast cancer after the start of the study and we know what they ate and when they ate it. We were able to ask about whether intermittent fasting affects breast cancer recurrence. We found that when women fasted for 13 hours during the night (for example, eating dinner at 7 and breakfast at 8) they had significantly reduced cancer recurrence,” she said. “So we’re excited about that.”
Sit on it … or better yet, don’t
Although little quantifiable data is available on the harmful effects of sitting for extended periods of time, Sears said she wants to be the one to find it.
“It’s true, across all ages, sitting too much is bad,” she said. “But the effects of sitting are under-studied. We do know that the length of uninterrupted sitting time is important and we need to find practical ways to break that up. But we don’t know how much (sitting) is too much, we don’t know what we should be doing when we’re not sitting, and we don’t know how to realistically change our behaviors.”
To quote the American Medical Association, she said the final word is: “sit less.”
In a pilot study to gather empirical data, Sears said her team is looking at using a new device, taped to the thigh, that can read if you are sitting (it registers as horizontal) or standing (it registers as vertical), which they can look at throughout the day.
“We found that every 10 additional sit-to-stands, going from a sitting posture to a standing posture and back down, the women had decreased inflammation and decreased insulin,” she said of the early results. “There’s a lot that we don’t know, but we’re committed to finding more information about that, and findings for real-world practical ways to interrupt sitting.”
Because sitting involves a “folded position,” the torso being vertical and the thighs being horizontal, she said she’d like to see how sitting affects blood flow, and measure how frequently people should stand for maximum benefit and for how long.
Using biological markers for diabetes, cancer and cardiovascular disease including glucose, insulin, blood pressure, heart rate, blood vessel functioning, Sears is working on a lab study while a colleague is working on a real-world study.
“We need new knowledge, improved measurement, why sitting is bad, how to break it up and evidence-based support of recommendations because the current recommendations of standing once an hour or every 90 minutes are not backed by science yet,” she said. Shy of quantifiable data, Sears simply advised that we should “get up, stand up.”
Sears’ presentation was part of the Howell Foundation speaker series, which focuses on women’s health, and named for its founder, Dr. Doris Howell. The next speaker will be Karen Possemato on “Unlocking the Power of the Genome,” Thursday, Aug. 25. For more information, visit howellfoundation.org
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