Eating a healthful diet — one that, in particular, includes plenty of fruits, vegetables, and whole grains and that limits foods high in added sugar — is associated with lowering the risk of heart attacks, stroke and other heart and blood vessel diseases.
But research suggests that when and how often we eat, not just what we eat, may also play a role in our heart health.
On Monday, a group of experts from the American Heart Association issued a scientific statement on that topic. After looking at all the existing studies on the relationship between the timing and frequency of our meals (including snacks) and heart health, they came to some interesting, if not definitive, conclusions.
Why is this important? Because, as background information in the AHA statement points out, Americans have dramatically changed the timing of their meals in recent decades. Today, only 59 percent of men and 63 percent of women report sitting down daily to three standard meals (breakfast, lunch and dinner), a decline from 73 percent (men) and 75 percent (women) in the early 1970s. Instead, Americans now tend to eat round the clock — anywhere from 4 to 10 meals or snacks daily.
Indeed, there is only a brief five-hour period when less than 1 percent of eating occurs: between 1 a.m. and 6 a.m.
That shift in meal patterns may have serious implications for the development of heart disease, type 2 diabetes and obesity, the AHA experts stress. For when we eat (and when we don’t) sends cues to our body’s internal biological “clocks,” which regulate all aspects of our metabolism.
One of the areas that the AHA statement focuses on is breakfast. According to current research, people who skip breakfast — an estimated 20 to 30 percent of adults in the United States — are more likely than breakfast-eaters to have high cholesterol and high blood pressure, two factors that raise the risk of developing heart disease.
They are also more likely to have impaired blood sugar metabolism, a factor associated with obesity and the development of type 2 diabetes.
“These risks seem to be independent of differences in diet quality between breakfast eaters and nonconsumers,” the AHA experts write.
But any health improvements associated with eating breakfast are “slight,” the experts also point out, and the studies that have shown such improvements have limitations. Most of the studies have been observational, for example, and therefore can’t prove a direct cause-and-effect between eating breakfast and better health.
So, for right now, as the AHA experts stress, no one can say with any certainty that people who currently skip breakfast would necessarily benefit from changing their schedule to include a morning meal. The experts do believe, however, that the evidence suggests a health benefit from consuming most of our daily calories earlier rather than later in the day.
Frequency and fasting
The information on meal frequency — another topic of the AHA statement — is also unclear. Some studies suggest that people who consume food more than three times a day tend to have lower cholesterol and a lower risk of obesity and type 2 diabetes than those who eat only once or twice a day. But, again, those studies were observational and therefore don’t prove that spreading calories across smaller meals throughout the day improves health.
Nor is there any solid evidence that frequent meals help with weight loss. In fact, as the AHA experts note, several controlled trials, ones in which people’s diet and health were carefully tracked, found that eating more frequently did not help lower the risk of obesity — or of heart disease.
The evidence does seems to suggest, however, that occasional fasting — that is, not eating one to two times per week or every other day — may contribute to short-term weight loss. Long-term studies on intermittent fasting have not been conducted, however, so it’s not clear if the practice helps keep the weight off.
Occasional fasting may also help lower blood pressure, although the research suggests that people have to lose at least 6 percent of their body weight for this benefit to kick in.
So what’s the bottom line? Based on their review of the current evidence, the AHA experts recommend an “intentional approach to eating,” which includes these elements:
- Distribute calories over a defined portion of the day.
- Eat a greater share of each day’s calories earlier rather than later in the day.
- Be consistent about fasting (not eating) each night.
- Consider intermittent fasting as a way of reducing unwanted body weight.
- Time your meals and snacks throughout the day to help manage hunger and achieve portion control.