A small study shows that the timing of meals can have a profound impact on blood sugar, insulin secretion and blood pressure. But what is the best time to eat? A reader is concerned that her late-night habit may be bad for her health.
Does Eating Late Raise Blood Pressure?
Q. I’m healthy with no known medical concerns, but over the past year, I’ve basically lost my appetite. I’ve lost over 40 pounds without trying at all. However, I’m aware that I need better nutrition to stay healthy.
The food I choose is high quality, but I’m simply not eating enough. So I’ve tried smoking marijuana to try and get some munchies going so I’ll feel like eating! This eventually works, but I’m a night owl. That means I eat late, shortly before I go to bed.
Recently I learned that my systolic blood pressure had spiked to over 140, when it had always been around 110 to 120. That was alarming. I happened across an article about the results of a longitudinal study where people self-reported their eating habits. It revealed, among other things: The later you eat, the higher your blood pressure!
Since reading that, I’ve been doing everything I can to either somehow eat earlier (barf) or not to eat at all (eek). By golly, my BP is already starting to come down. What can you tell me about this?
A. We have searched the medical literature to find the study you mention and come up with very little. (Keep reading for the research we have found.) Scientists have not focused much research on the relationship between late meals and blood pressure, although one study from Korea found no link (Epidemiology and Health, Nov. 24, 2021). Many more studies have focused on how eating late affects weight and blood sugar.
You should ask your physician for a thorough check up to find the cause for your lack of appetite and weight loss. An overactive thyroid gland could lead to weight loss and make it hard to fall asleep. Undiagnosed diabetes might also lead to weight loss. We checked to see if cannabis might have raised your blood pressure, but research does not support that link, either (Scientific Reports, Feb. 5, 2023). If you possibly can, eating earlier would be healthier than not eating at all.
Finding the Best Time to Eat:
Many Americans eat their biggest meal at dinner time. Based on the new research, that timing might be a mistake (Sutton et al, Cell Metabolism, June 2018).
In this pilot study, eight men with prediabetes had five weeks of normal meal times as a control. That is, breakfast, lunch and dinner, at approximately the usual times for those meals. The same group was then tested under the early time-restricted feeding formula. In this phase of the trial, they ate breakfast between 6:30 and 8:30 every morning. They had to finish dinner no later than 3:00 pm. They then fasted for the rest of the day. There were no evening meals or late-night snacking.
A Long Fasting Period Improves Metabolism:
Although they ate the exact same foods during the time-restricted feeding phase, the men experienced better insulin sensitivity. Surprisingly, their blood pressure also came down significantly. Measurements of oxidative stress also showed improvement.
The researchers conclude that eating earlier in the day appears to have measurable health benefits, whereas eating late at night is bad for metabolism. They point out that intermittent fasting has benefits beyond simply eating less. People need to pay attention to their circadian rhythm when they plan their meals. The research may have particular relevance to people who are prone to type 2 diabetes and hypertension.
Previous Research on the Best Time to Eat:
This is not the first study to show that we may do well to avoid late-night meals. An Israeli study found that people lost more weight and controlled their blood sugar better if they ate a big breakfast, a moderate-sized lunch and a small supper. That pattern was compared to six small meals evenly spaced throughout the day.
In an earlier study, volunteers ate either a large lunch or a large supper, following random assignment. Those who ate more calories at midday lost more weight than those who consumed them in the evening.
Learn More:
We discussed meal timing and intermittent fasting with Dr. Marie-Pierre St-Onge in Show 1094: Does It Matter When You Eat?
