Q&A #3: Time-restricted eating vs. calorie restriction, fueling for long runs, how to reduce resting heart rate, and more!
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Q: Do you have any suggestions for someone running a marathon who is low carb in general? She gets GI distress when she eats Gu or carb loads during a run. Are there any good energy sources for her fueling during a long run?
A: For many people, energy gels and other higher-sugar products can lead to gastrointestinal distress due to the problem of absorption. I’m going to speculate that her issue with tolerating an energy gel (or anything higher in carbohydrates during a run) is because she hasn’t “trained her gut” enough. Training the gut just means practicing consuming carbs and other types of food during a run so that the body can learn how to digest “on the go.” Another reason for her “intolerance” is probably her low-carb diet. If she isn’t regularly eating carbs and then introduces them before or during a run, this could lead to issues with digestion/absorption as well.
The good news is that there are plenty of alternatives! One of the products that I’ve seen recommended by low-carb endurance athlete Zach Bitter is called SFuels (no affiliation). I would certainly look into that.
Other whole-food options can work well to fuel longer efforts. Low-carb options could include nuts and nut butter, which can be easy on the stomach. But since some carbohydrates can likely help anyone during a workout, other options could include pretzels, regular or dried fruit, granola, or pre-packaged energy bars. Deciding what to eat before and during a workout is a process of experimentation — learning what your body responds well to and what it can tolerate.
Q: What is the typical difference between your average resting heart rate and lowest resting heart rate with your OURA ring? I wonder why the homepage shows the lowest resting heart rate overnight instead of the average. Any ideas?
A: I typically have about a 3-5 beats per minute difference between my average resting heart rate (around 38-40 bpm overnight) and my lowest resting heart rate (around 34-38 overnight).
I can’t find anything on the OURA website as to why they use the lowest versus average when giving your resting heart rate on the homepage. However, if you open the details for any particular night, you can get both the lowest and average resting heart rate. I do think that the lowest heart rate during the night has some physiological importance. Per the OURA site, it seems beneficial to have a “hammock-shaped” heart rate profile overnight — with your lowest heart rate occurring near the midpoint of sleep. This could indicate that your sleep and activity patterns are in line with our normal circadian rhythms.
I also found some interesting data from OURA if you’re interested in how your resting heart rate compares to the average OURA user. Here are the average lowest resting heart rates by age and sex. The average for women is 58 beats per minute and for men, it’s 55 beats per minute.
Q: Is there any advantage to time-restricted eating (TRE) over simple calorie restriction? What does the evidence say?
A: Increasingly, it seems like the benefits of TRE/intermittent fasting may largely be due to a reduction in calories. In other words, there (probably) isn’t any advantage to TRE over simple caloric restriction for weight loss or changes in body composition. There may be some unique benefits from TRE with regard to reducing cardiometabolic risk factors. It’s all going to depend on which study you read. Below is a nice infographic from a paper published in the New England Journal of Medicine that found no differences between TRE and standard caloric restriction.
But I certainly think that TRE and intermittent fasting have their place in weight loss/metabolic health improvement. It appears that many people find it easier to reduce their energy intake using something like TRE — reducing when/how often they eat instead of consuming smaller portion sizes at each meal. If that’s the case, then I’d say there is an advantage to different types of intermittent fasting.
Also, some data indicate that TRE and intermittent fasting may be more beneficial in people who have cardiometabolic risk factors or who have obesity, diabetes, or other types of metabolic disorders.
Q: What if instead of a high step count each day, I get on the exercise bike? Is that enough?
A: Research indicates that we should be achieving 7,000-10,000 steps per day in addition to whatever structured daily exercise we are engaging in. To put this another way, a workout in the morning or the afternoon may not compensate for an entire day spent sitting. In fact, if you get less than 5,000 steps per day, this might actually hinder the benefits of exercise — a concept that’s being called “exercise resistance.” Of course, this doesn’t mean that you won’t benefit from exercise if you don’t walk enough, only that the benefits for metabolism may not be as great as they otherwise could be.
My recommendation based on the evidence would be to have a daily “background” of physical activity equal to the 7-10,000 steps mentioned above and continue to hop on the exercise bike or engage in whatever exercise modality you choose to do on a particular day.
Q: Do diet and exercise automatically lower resting heart rate, or are there other things that can be done to work it down beyond medication?
A: Diet alone probably won’t have an impact on your resting heart rate, unless a dietary change is accompanied by weight loss. In that case, weight loss would likely correspond to a lower resting heart rate, with the magnitude of change in heart rate related to the magnitude of weight loss.
As for exercise, this is probably one of the best ways to reduce resting heart rate. As our aerobic fitness increases, our resting heart rate will decrease. This happens because as our heart gets stronger, our stroke volume (how much blood our heart ejects during each contraction) increases. To pump the same amount of blood throughout the body, heart rate goes down, but we’ll still distribute the same amount of blood (our cardiac output stays the same).
One other factor influencing resting heart rate is our autonomic nervous system activity. At rest, heart rate is governed by the parasympathetic nervous system
Increasing parasympathetic (vagal) tone to the heart can decrease resting heart rate. However, I’m not aware of training techniques (other than exercise) than can improve vagal tone. Reducing sympathetic innervation to the heart (i.e., stress reduction) may also be beneficial for reducing resting heart rate.
Thanks for reading!