School of Biomedical Sciences, Kent State University, Kent, OH 44242, United States.
Department of Physiology and Pharmacology, The University of Toledo College of Medicine and Life Sciences, Toledo, Ohio 43614-2598, United States.
Physiol Behav. 2021 Mar 1;230:113280. doi: 10.1016/j.physbeh.2020.113280. Epub 2020 Dec 5.
Intermittent fasting (IF) strategies have emerged as viable alternatives to traditional calorie-restricted diets. A key predictor of metabolic health and response to diet is cardiometabolic fitness, including intrinsic aerobic capacity. In a contrasting rat model of aerobic capacity-high- and low-capacity runners (HCR, LCR)-we found that the lean and physically active HCR were also more responsive to a standard calorie-restricted diet. Here, we assessed the ability of IF to induce weight loss on a background of high and low aerobic fitness accompanied by different levels of daily physical activity.
Female HCR and LCR (8 per line) were subjected to IF (alternate-day fasting) for 14 weeks. Outcomes included changes in body weight, fat and lean mass, daily physical activity, and food and water intake. After initial measurements, IF was continued, and measurements were repeated after one year of IF.
All rats lost weight with IF, and LCR lost significantly more weight than HCR. This difference was primarily due to differential fat loss; loss of lean mass, on the other hand, was similar between HCR and LCR. Total food intake decreased with IF, and LCR showed lower intake than HCR only during the first 5 weeks of IF. Physical activity was suppressed by long-term IF. Physical activity increased on fed days compared to fasted days, and this pattern was more pronounced in HCR. The differential effects of IF in HCR and LCR persisted after one year of IF, with IF preventing the marked weight gain seen in ad libitum fed LCR during this time.
Weight and fat loss from IF was more pronounced in obesity-prone, low-aerobic capacity LCR, despite the low activity levels seen in these rats. The possibility that aerobic capacity modulates response to IF in human participants remains unexplored.
间歇性禁食（IF）策略已成为传统热量限制饮食的可行替代品。代谢健康和对饮食的反应的一个关键预测因素是心脏代谢适应性，包括内在的有氧能力。在有氧能力高和低的对比大鼠模型中（高能力跑步者 [HCR] 和低能力跑步者 [LCR]），我们发现，瘦且活跃的 HCR 对标准热量限制饮食的反应也更敏感。在这里，我们评估了 IF 在高和低有氧适应性背景下诱导体重减轻的能力，同时伴有不同水平的日常体力活动。
将 8 只雌性 HCR 和 LCR 分别进行 IF（隔日禁食）14 周。结果包括体重、脂肪和瘦体重的变化、日常体力活动以及食物和水的摄入。初始测量后，继续进行 IF，并在 IF 一年后重复测量。
所有大鼠在 IF 期间体重均减轻，LCR 体重减轻明显多于 HCR。这种差异主要是由于脂肪的差异丢失；另一方面，瘦体重的损失在 HCR 和 LCR 之间相似。IF 会减少总食物摄入量，而且 LCR 仅在 IF 的前 5 周内的摄入量低于 HCR。长期 IF 会抑制体力活动。与禁食日相比，进食日的体力活动增加，这种模式在 HCR 中更为明显。IF 在 HCR 和 LCR 中的差异作用在 IF 一年后仍然存在，IF 防止了这段时间内自由喂养的 LCR 出现明显的体重增加。
尽管这些大鼠的活动水平较低，但在肥胖易感、低有氧能力的 LCR 中，IF 引起的体重和脂肪减轻更为明显。有氧能力是否调节人类对 IF 的反应仍有待探索。
