I think this is a result of a body that is more fit.
According to NEMA, most "normal" people's pulse rates fall within 60 and 90. But remember that they are testing the general population (having eaten a modern neolithic diet for a century) and those numbers are going to represent what's normal for a modern neolithic society. This website also states that athletes tend to have lower ranges, between 40 to 60.
So if you're otherwise fit, still experiencing good energy levels and mental clarity, you're probably fine. However, if you're experiencing other symptoms, such as low energy or dizziness, it might not be the paleo diet. It might be something else and you should see a doctor.
I practice IF and usually when I check my pulse I do it at night during the feeding window. I don't recall checking my pulse in the fasted window so I tried this just now. My pulse range is usually 54-56 but my current pulse is 49!
I found a study done on rats to determine the affects of Dietary Restriction and IF on many factors, including heart rate. The study showed that DR and IF produce a lower heart rate compared to eating Ad libitum.
Heart rate and blood pressure
HR in both groups decreased gradually in response to the initiation of both DR regimens, and although the trend was similar in both periods, the effect appeared more significant during the dark period than in the light period (Fig. 2 A). From DR wk 2–8, HR was reduced significantly compared with pre-DR measures in the same rats (P<0.05). In addition, HR during DR wk 3–8 was significantly decreased compared with that in wk 1 (P<0.05). These results indicate that the IF- and CR-induced reductions in HR reach a maximal effect at 3–4 wk after the diets were initiated in both groups. However, DR-induced reductions in HR were rapidly reversed after food was made available AL. Although HR during wk 1–3 after AL diet resumption was lower than pre-DR in the same group (P<0.05), this difference was not significant 4 wk after the AL regimen was resumed. The magnitude of the effects on HR produced by either IF or CR were similar.
If you IF this may be causing the decreased HR. Interesting!
Mine started to drop even before I started eating totally paleo. I started out trying the Shangri-La Diet, got some pretty good appetite suppression, and started restricting the calories to around 1500. My pulse dropped; in fact, one day I had them test me in the office because I felt funny- blood pressure was low as well.
My pulse has reduced. Before I started eating paleo my pulse was in the high 90s. Currently it's 62. The most interesting detail is the change can be attributed to diet rather than exercise. This since I haven't exercised much since changing my diet. I haven't lost an exorbitant amount of weight either. Since going completely diet-paleo in February I've only lost ~22 lbs. That's approximately 35 lbs away from my ideal weight. I'm only now feeling healthy enough to start exercising. Due to a bad toe joint, walking isn't in the cards. But I intend to start doing yoga and maybe riding a Trikke once in a while.
I was going to ask a similar question to this but i thought i'd bump this old thread instead. I've just taken my resting pulse rate (sat at desk, middle of the afternoon) and it's 35/36! Last time i remember checking it was in the mid 40s. I think it must be a combination of low carb and intermittent fasting - i haven't eaten since yesterday evening.
Before I started the paleo diet a year ago, my pulse was 75-80. After a couple of months on the diet and a little bit of exercise, I got it down to 53 on average. It even went down to 48 a couple of times. I later stopped exercising and it went up to 60. About two weeks ago, I started exercising again and it's about 53. ( Just a couple of minutes ago, I checked it a few times in a row and I was at 49). Feel great. Lots of energy. Definitely the way we were meant to eat. Been on it for a little over a year and no longer crave grains, sugar or dairy.
After a few years paleo, all of that saturated fats starts clogging the arteries. As a result the heart will stop for several days at a time... I'm posting this with a stopped heart, its just resting you know.