Temperature and Pulse Basics & Monthly Log

Also see:
Ray Peat, PhD on Thyroid, Temperature, Pulse, and TSH
Low Carb Diet – Death to Metabolism
Body Temperature, Metabolism, and Obesity
Thyroid, Temperature, Pulse
Metabolism, Brain Size, and Lifespan in Mammals
Promoters of Efficient v. Inefficient Metabolism
Inflammation from Decrease in Body Temperature
Melatonin Lowers Body Temperature
Menopausal Estrogen Therapy Lowers Body Temperature
Thyroid Function, Pulse Rate, & Temperature
“Curing” a High Metabolic Rate with Unsaturated Fats
Fat Deficient Animals – Activity of Cytochrome Oxidase
Comparison: Carbon Dioxide v. Lactic Acid
Carbon Dioxide Basics
Energy Flow: Plant World and Animal World
Biological Energy & Matter Cycle
Is 98.6 Really Normal?

Metabolism is the sum of chemical processes that occur in an organism in order to maintain life. Life depends upon the continual conversion of fuel substrates into chemical energy, allowing cells to perform biological work. Heat is produced by these cellular metabolic processes so the resting metabolic rate can be predicted accurately by the rate of heat production.

The unifying principle of Ray Peat, PhD’s work in FPS’ opinion is that energy production from cellular respiration/metabolism allows for structure and function of cells to be optimized, and this improved structure and function promotes continued high energy output as well as the production of protective steroid hormones and carbon dioxide.

Anything that interferes with energy production has opposing effects, slowing energy output, the consumption of oxygen, and the production of protective hormones and carbon dioxide. The ability to produce energy is at the center of health v. non health, youth v. aging, etc.

A simple way to monitor the intensity of your resting metabolism (i.e. how well you are making energy/heat) is to track the resting oral temperature and pulse rate. Collect this data upon waking while lying in bed, ~40 minutes after breakfast, and between 1 and 3 pm in the afternoon.

Prior to 1940, the resting body temperature upon waking was a common way in which physicians would diagnose a slow metabolism. If the temperature was below optimal, a trial of natural desiccated thyroid was given. If symptoms regressed as metabolic efficiency improved and temperature rose from the thyroid supplementation, the therapy was continued. Broda Barnes, MD, PhD and other doctors influenced by his work use this method during his career with much success.

Here are some temperature and pulse tracking basics:
1. Before taking each reading, be at rest for at least five minutes. Use a basal thermometer or mercury thermometer for oral temperature accuracy. An oximeter (like one from Santa Medical) can help you quickly track your pulse. If you don’t have an oximeter, count your heart beats at the neck or wrist for a full 60 seconds or count for ten seconds and multiply by six.
2. Temperature or pulse should not decrease following meals. If it does this consistently, adrenal stress hormones are playing a significant role in your physiology. The introduction of sugar from food lowers the stress hormones and provides a more clear outlook on the resting metabolism.

“If the night-time stress is very high, the adrenalin will still be high until breakfast, increasing both temperature and pulse rate. The cortisol stimulates the breakdown of muscle tissue and its conversion to energy, so it is thermogenic, for some of the same reasons that food is thermogenic.

After eating breakfast, the cortisol (and adrenalin, if it stayed high despite the increased cortisol) will start returning to a more normal, lower level, as the blood sugar is sustained by food, instead of by the stress hormones. In some hypothyroid people, this is a good time to measure the temperature and pulse rate. In a normal person, both temperature and pulse rate rise after breakfast, but in very hypothyroid people either, or both, might fall.” -Ray Peat, PhD

3. Upon waking, an ideal temperature is between 97.8-98.6F and a pulse rate between 75-85 beats per minute (BPM). Other readings during the day should fall within these parameters as well with temperatures being closer to 98.6F than 97.8F. Data points below the optimal are a sign of a slowed metabolic rate.
4. There should be an increase in temperature and pulse rate following a good breakfast as the liver becomes energized allowing it to form the active thyroid hormone, triiodonthyronine (T3).
5. The afternoon temperature and pulse should increase relative to the morning readings because of the thermogenic effect of good nutrition and movement, and the metabolic stimulation from light.
6. In some individuals with overactive adrenal stress hormones (adrenaline/cortisol), the temperature and pulse rate may seem optimal despite symptoms that indicate otherwise. In such people, the temperature and/or pulse will start to drop when metabolic efficiency starts to be restored. This is a sign of progress. Anything consistently over the optimal readings is either a sign of hypermetabolism or an exaggerated adrenaline/cortisol response.
7. Correlate the temperature and pulse rate data to the person. The temperature and pulse information serves as one piece of data that needs context to be understood completely.
8. The ease by which this data can be taken and tracked makes it ideal in discovering which foods, supplements, and activities promote or degrade your metabolism.
9. If you can’t get all three readings due to lifestyle/work commitments during the weekdays, do your best to at least get the waking temperature/pulse and be religious about getting all three readings on the weekend. Setting an alarm or event in your calendar on your phone can serve as a reminder until tracking becomes more habitual.
10. Both the temperature and pulse rate provide more data together than either one of them alone.

Click the link below for a .pdf of a Monthly Temperature and Pulse Log to print and use.
Temperature and Pulse Log by FPS

KEY for the log:
WT/P = Waking Temperature/Pulse
ABT/P = After Breakfast Temperature/Pulse
AT/P = Afternoon Temperature/Pulse

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9 Responses

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  1. Coconutgal says

    Thank you, very useful information.

  2. Michelle says

    Hey guys, do you have more written on this with regards to athletes? I’ve read Ray Peat’s articles also, and would like a more thorough investigation into low resting heart rates in athletes and what this means in terms of health.
    Cheers legends, Michelle Drielsma.

  3. ryan says

    Hi Rob, how should the pulse rate react after exertion i.e. is there a safe % range that it should stay within? I ask because my resting rate is in the 75-85 range but any slight exertion like climbing a flight of stairs causes my breath and pulse to quicken quite a bit. What would you think this ‘breathlessness’ after moderate exertion means ?

  4. Team FPS says

    That’s a normal reaction to exertion. An estimated maximum heart rate can be determined via the following formulas:

    Men: 220 – age = maximum heart rate
    Women: 206 − (0.88 × age) = maximum heart rate

    Multiply the maximum heart rate by 50-60% to determine what your estimated heart rate after moderate activity.

  5. Zach says

    What mechanism is at play when the afternoon temps and pulse rate are 99, but wake up temps are still 96.5? I know there should be a strong daily cycle, but usually within a degree, not 2 or 3. I should also mention that I have been following many of peats recommendations, and despite great oral temps, my feet are cold 90% of the time.

  6. Team FPS says

    Looks like your adrenaline is high during the daytime and, in turn, your liver glycogen isn’t sufficient enough to keep your metabolism higher during the night. The elevated daytime adrenaline idea is also supported by your cold feet, which is evidence that the circulation is being diverted. See the first link below for more on this concept. As your metabolic efficiency improves, suspect that your temperature and pulse rate will drop during the daytime as adrenaline decreases.

    Stress — A Shifting of Resources

    Ray Peat, PhD on Thyroid, Temperature, Pulse, and TSH

Continuing the Discussion

  1. Foods that Prevent Aging Skin: A Nutritionist's Tips | Beauty Editor linked to this post on February 25, 2014

    […] ** A healthy body temperature sits above 36.6 C / 97.8 F a sign that cell metabolism is being supported. You should see a rise in temperature after eating, with a resting pulse ideally between 75-90. More on this here. […]

  2. Misconceptions in Exercise and Stress | linked to this post on June 30, 2014

    […] can get an idea of how stress is affecting your metabolism with biofeedback like temperature ( ) or noticing symptoms (poor digestion, low sex drive, cold hands/feet, irregular menses). Many of […]