Billingsley HE, Dixon DL, Canada JM, et al. Time of eating and cardiorespiratory fitness in patients with heart failure with preserved ejection fraction and obesity. Nutr Metab Cardiovasc Dis. 2021;31(8):2471-2473.
To examine the effect of timing of evening meal consumption on the cardiorespiratory fitness (CRF) of patients with heart failure with preserved ejection fraction (HFpEF) and obesity.
A cross-sectional, observational pilot study.
The study included 12 patients (9 women, 3 men) aged 52 to 65 years with: stable, symptomatic (New York Heart Association Class II–III) HFpEF (left ventricular ejection fraction ≥50%). All participants had concomitant obesity (body mass index [BMI] ≥30 kg/m2 or fat mass percentage [FM%] of body weight ≥25% for men or ≥35% women).
Study Parameters Assessed
Three consecutive, 5-pass, 24-hour diet recalls were completed for each participant. Based on their responses, evening meal times of the day were averaged for the individual, as well as the whole group, and then participants were assigned either to Group I (eating meals before the group average of 7:25 pm) or Group II (eating meals after the group average of 7:25 pm) for analysis.
Researchers used bioimpedance analysis to measure participants’ fat mass and fat-free mass.
Researchers administered maximal cardiopulmonary exercise tests to each participant and measured the following to assess cardiorespiratory fitness:
- peak oxygen consumption (VO2) compared to body weight and fat-free mass
- percent predicted peak oxygen consumption
- exercise time
- oxygen pulse
- oxygen uptake efficiency slope (OUES) and oxygen uptake efficiency plateau (OUEP)
- serum N-terminal pro B-type natriuretic peptide (NT-proBNP)
Primary Outcome Measure
The primary outcome measure was any statistically significant differences in cardiorespiratory fitness between Group I and Group II.
Group II (those who consumed their evening meals after 7:25 pm) had significantly better cardiorespiratory outcomes compared to Group I. There were significantly better measures of peak oxygen consumption (peak VO2; P=0.028), peak oxygen consumption compared to fat-free mass (P=0.019), and exercise time (P=0.007), compared to those who consumed evening meals before 7:25 pm.
Intermittent fasting and other forms of time-restricted eating are becoming ever-more popular, with many citing these dietary changes as treatment for a number of health conditions beyond the most obvious, weight loss.1 These strategies usually involve consuming meals in an 8- to 10-hour window, often earlier in the day. While there have been a number of well-designed trials demonstrating benefits with time-restricted eating for weight loss in people with obesity,2,3 there is some evidence that this may have more impact on lean mass and may actually predispose obese individuals to reduced physical activity.4 Both reduced fitness and muscle loss can adversely affect overall cardiorespiratory fitness, a known prognostic factor in heart-failure patients.
The authors of this study investigated (in a small group of older adults with heart failure and obesity) whether the timing of an individual’s evening meal had any influence on their cardiopulmonary health. The theory proposed is that there is additional stress put on the heart during the fasting state that could result in poorer cardiorespiratory fitness. The study results did, indeed, suggest that those who ate later at night had significantly better cardiorespiratory fitness, with approximately 50% higher peak VO2 and VO2 FFM and 50% longer exercise-time durations than those who ate earlier in the evening.
This news may surprise some and challenge assumptions held by many conventional and naturopathic practitioners. Late-night eating is generally frowned upon in lifestyle medicine. A common recommendation for digestive issues and sleep disturbance is refraining from eating evening meals at a late hour, though the evidence to support this recommendation may be quite limited.5-7 Late-night eating is often synonymous (though, possibly inaccurately) with overeating and “snack food,” so it is also a frequent focus during the management of obesity, dysglycemia, insulin resistance, and metabolic disorder.
The study under review here was a 2-page article. While succinctness can be extremely satisfying in comparison to the long-winded research manuscripts we often see, the researchers left unanswered many relevant details of the study design that would better inform the context of these results.
This news may surprise some and challenge assumptions held by many conventional and naturopathic practitioners.
For example, exactly how did the researchers define the evening “meal” in this study? Was it the time of the last large, formal meal of the participants’ day (ie, dinner)? What about postdinner snacking? And if the participants snacked after dinner, did that change the group assignment? Also, while the authors suggest that “TRF [time restricted feeding] may pose an additional stress of the heart…while providing nutrients later in the evening might provide the heart with energetic substrate ultimately avoiding a fasting-related stress,” this is not a reasonable inference. A person can eat late at night and be “intermittent fasting” into the afternoon the next day, and another person can have their last evening meal early but have started eating 12 hours or more prior (for example). A more reasonable proposal that can be drawn from these results is that the act of eating meals later at night appears to have a protective effect on cardiorespiratory fitness in obese individuals with heart failure than in similar patients who eat their evening meals earlier; whether this is more broadly applicable to other time-restricted eating schedules is unknown.
It would be worth clarifying what time of day the participants underwent the study assessments in relation to their last meal (or last evening meal). On the day of the assessment test, had the participants eaten prior to their test? How close? Presumably this would have been kept consistent amongst the participants, though the article does not specify this, and it could conceivably have had an impact on the energy requirements for the participants’ physical performance. Also, while researchers calculated individual caloric intake, the small sample size makes it difficult to do proper analysis to account for the differences.
The authors also do not disclose how they recruited the participants. Nine of the 12 participants were women. Women, especially those in the menopausal age range (as were those included in this study), have unique cardiovascular and weight-loss-related challenges that could differ significantly from men. Previous studies have actually shown late-night eating increases risk of metabolic syndrome, but only in men.8 Could the apparent benefits of late-night eating demonstrated in this study be attributed to a lack of enough male participants to show detrimental effects? Given the sample size was so small, a lack of participant diversity could have easily skewed these results.
Without a controlled intervention, this study has limited applicability also due to its observational design. While the results may give us pause in recommending against late-night eating in this particular patient population, clinicians should have little concern about moderate restricted-eating strategies in otherwise generally healthy individuals. Heart-failure patients have altered whole-body metabolism compared to healthy controls, including an increased reliance on fatty acids for energy production.9-11 Time-restricted eating in these individuals, especially over time, may deplete the heart of its primary reservoir of adenosine triphosphate (ATP), resulting in poor cardiorespiratory fitness. Eating meals later at night may simply allow for these patients’ body to be in a “fasting state” overnight for less time, ultimately decreasing the amount of time the cardiac tissue is suboptimally nourished. However, it is worth noting that NT-proBNP (a strong predictive biomarker of heart-failure outcomes) did not differ significantly between the groups in the study, suggesting that the impacts on cardiorespiratory fitness from late-night eating may not be solely related to heart health. Further exploration into exact mechanisms of actions would give a more definitive answer.
If alterations to energy metabolism are a key mechanism of action in explaining how eating earlier in the evening decreases cardiorespiratory fitness in obese heart-failure patients, then supporting these metabolic challenges, directly and indirectly, would be a reasonable treatment strategy for protecting against cardiorespiratory decline. Common naturopathic treatments for supporting cardiomyocyte function include omega-3 fatty acids,12 l-carnitine,13 and coenzyme Q10;14 these are likely particularly relevant for managing the heart’s energy use and expenditure.
Obesity decreases cardiorespiratory fitness and increases the risk of developing heart failure, but an obesity paradox exists within already diagnosed heart-failure patients in which poorer outcomes and prognosis are associated with leaner mass.15 The caloric restriction often involved in managing weight may be an ill-placed primary treatment for these individuals. Some people who are obese may also have less capacity for physical exercise (as well as the blunted weight-loss response to exercise in patients with higher BMI/adiposity16), driving them to prioritize dietary restriction as a primary means to weight loss.
This study is a good reminder to clinicians that various disease states have different metabolic underpinnings. This is relevant to any patient, but especially in those who are additionally struggling with weight management. With more specific nutrient research, such as this study, emerging to challenge our traditional approaches to diet and eating, hopefully there is a call for more controlled clinical trials to investigate and validate these innovative clinical theories. Meanwhile, in light of the possibility of adverse effects from fasting states in those with heart failure, it may be prudent to focus on strategies other than time-restricted eating in this patient population for potentially improving prognosis and preventing decline.