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Thomas DeLauer Recap: Cortisol, a "Flat" Daily Curve and Insulin Resistance

Takeaways and a chaptered guide to Thomas DeLauer's video on cortisol and insulin resistance: the 1982 cortisol-infusion study, why he thinks the shape of the daily cortisol curve matters more than its level, morning light, and his links to testosterone, thyroid and gut health.

By the GNOUP team · · 8 min read

The latest full video on Thomas DeLauer's official YouTube channel, "They Injected Cortisol Into People and This is What it did to Insulin Resistance (real study)", was posted on November 12, 2026 and runs about 12 and a half minutes. DeLauer, a fitness and nutrition content creator, talks solo about cortisol, the body's main stress hormone. He starts with an older study in which cortisol was infused into healthy volunteers, then argues that the real problem for many people is not cortisol being "too high" all the time but a daily cortisol rhythm that has gone flat. He ties that idea to sleep, testosterone, thyroid function and gut health, and ends with the habits he favors. The title is his framing; this article makes no promises about results.

This is an independent summary written by GNOUP. It is not affiliated with, sponsored by or endorsed by Thomas DeLauer, his channel, website or any sponsor. The views and claims described below belong to the speaker, not to GNOUP. This is general information only and is not medical advice. Insulin resistance, blood sugar problems and hormone issues need proper medical care, so please talk with a doctor before changing your routine, diet or supplements. This matters especially if you have a medical condition (including diabetes or a thyroid condition), take any medication, are pregnant or breastfeeding, are under 18, or have a history of an eating disorder. GNOUP has no connection to any product, supplement, brand or paid offer mentioned in or around the video and does not promote any of them.

Key health tips and takeaways

These are ideas DeLauer shared in the video, not instructions. We do not include amounts, schedules, supplement protocols or exposure times.

  • The infusion study. DeLauer describes a study in which researchers raised cortisol in healthy people to about four times normal, a level he compares to moderate-to-severe stress. In his telling, their cells still responded to insulin, but needed noticeably more of it to do the same job, in both the liver and other tissues such as muscle.
  • A jammed signal, not a broken lock. He says insulin still attached to cells normally in that study, and that the problem was further down the signaling chain. His analogy: the garage door works, but the clicker signal is being jammed. (See the note below about which parts of this come from the study itself.)
  • Why it matters day to day, in his view. He argues that ongoing poor sleep, work or relationship stress, and cortisol that stays up in the evening can keep that same mechanism running night after night, and suggests this may be one reason some people who eat carefully still see fasting glucose creep up. That is his interpretation, not a diagnosis.
  • The "flat curve" idea. His main point: in a healthy rhythm, cortisol rises sharply in the first part of the morning and then falls through the day to a low point around midnight. He believes modern habits (mostly indoor light, screens first thing in the morning, late eating and alcohol) blunt the morning peak and keep evening levels from dropping, leaving a flatter line.
  • Why he says "just lower cortisol" can backfire. Because of that, he argues the goal is not low cortisol across the board but a steeper curve: higher in the morning and lower at night. He says trying to suppress cortisol all day may leave some people feeling worse.
  • Morning light as the first lever. He calls outdoor light soon after waking the simplest, free habit for sharpening the morning peak, setting the timing of the evening sleep hormone melatonin and, in his view, lowering evening cortisol. We have left out the specific minutes and timing he suggests. Please protect your skin and eyes and never look at the sun.
  • Cold, only if you already do it. He says he does not suggest adding cold exposure if you do not already use it, but mentions that some people pair morning cold or splashing cold water on the face with morning light. Cold exposure is not safe for everyone, especially people with heart or blood-pressure conditions, so ask a doctor first.
  • Evening wind-down. For the evening side of the curve he mentions an earlier dinner and cutting back on late screens.
  • One pattern behind several problems. He closes by saying insulin resistance, poor sleep, low testosterone, a "sluggish" thyroid and gut trouble can all trace back to one flattened cortisol curve. That is a broad claim that GNOUP has not verified; these conditions have many possible causes and deserve a proper medical workup.

Newsworthy insights

These are claims and opinions from the video. GNOUP checked the five references linked in the video's description on PubMed (see below), but has not verified every statement made about them.

  • The cortisol infusion study. The linked paper is Rizza, Mandarino and Gerich, Journal of Clinical Endocrinology and Metabolism, 1982. Its abstract describes six healthy volunteers given a 24-hour cortisol infusion that raised cortisol about fourfold, with insulin dose-response curves shifted to the right, normal maximal responses, no drop in insulin binding, and a conclusion that the resistance is explained by a "postreceptor" defect. The specific molecular step DeLauer names (IRS-1) is not mentioned in that abstract; it is his explanation of the mechanism.
  • The morning light study. The linked paper is Leproult and colleagues, Journal of Clinical Endocrinology and Metabolism, 2001. The abstract describes eight healthy men during 36 hours of continuous wakefulness; a 3-hour bright-light period in the early morning produced an immediate rise of more than 50% in cortisol, while the same light in the afternoon had no effect. Note that this was done in sleep-deprived volunteers in a lab, not in people following a normal routine, and the abstract does not give the exact minutes he quotes.
  • Cortisol and testosterone. He says cortisol suppresses testosterone at several points along the brain-to-testes pathway, and that body fat can convert more testosterone to estrogen. No reference was linked for this part.
  • The supplement study. He cites a trial in the American Journal of Men's Health on an herbal extract in overweight men. The linked paper (Lopresti and colleagues, 2019) is a crossover trial with two 8-week periods (16 weeks in total), not a 16-week course; its abstract reports an 18% greater increase in DHEA-S and a 14.7% greater increase in testosterone versus placebo, but also no significant differences in cortisol, fatigue or vigor, and calls for larger studies. DeLauer also mentions several supplements in his closing "protocol". We have left those out of the tips, along with any amounts, because supplements can interact with medications and are not right for everyone. Please ask a doctor or pharmacist before trying any of them.
  • Thyroid. He says cortisol can slow the conversion of thyroid hormone to its active form, so labs may look normal while tissues get less of the active hormone. No reference was linked; treat this as his claim, and talk to a doctor about any thyroid concerns.
  • Stress and the gut. The linked paper is Vanuytsel and colleagues, Gut, 2014. Its abstract reports that a public-speaking stress test increased small-intestinal permeability in healthy volunteers only in those whose cortisol rose significantly, and points to mast cells and corticotropin-releasing hormone (CRH, a stress signal from the brain) rather than cortisol itself as the trigger tested.
  • Fermented foods. The last reference is Wastyk and colleagues, Cell, 2021, a 17-week randomized study (18 people per group) in which a high-fermented-food diet increased gut microbe diversity and decreased inflammatory markers. The abstract does not give the "19 markers" figure he mentions and does not mention cortisol, so that link is his interpretation.

Watch the video

They Injected Cortisol Into People and This is What it did to Insulin Resistance (real study) on YouTube (official channel "Thomas DeLauer," @ThomasDeLauerOfficial, published November 12, 2026, about 12 minutes)

Episode guide

These chapters come from the video's own description (titles lightly reworded). Each link opens the video at that point.

About this summary

This recap was prepared from the video's title, description and chapter list, and a transcript of the video. We left out a paid sponsor segment for an online grocery service, along with its discount and offer, as well as all supplement names in his closing routine, supplement and study doses, light-exposure minutes and timing windows, his newsletter and social links, and a plug for another of his videos. Transcripts can contain errors, so for the exact words and context, watch the video. This article is general information, not medical advice, and is not a substitute for guidance from a doctor or other qualified healthcare professional.