Expert Q&A

Can you take vitamin D with a tbsp of oil on an extended water fast for people with insulin resistance

Vitamin D and Fat-Soluble Absorption Basics

As the founder of CFP Weight Loss and author of The Metabolic Reset Protocol, I frequently address questions from people aged 45-54 struggling with insulin resistance, hormonal shifts, and joint pain that makes traditional exercise difficult. Vitamin D is critical for these individuals because deficiency worsens insulin resistance, inflammation, and blood sugar control. However, vitamin D is fat-soluble, meaning it requires dietary fat for optimal absorption in the intestines. Taking it dry during an extended water fast often results in only 10-20% bioavailability according to metabolic studies.

A tablespoon of oil, particularly MCT or olive oil, can boost absorption dramatically—up to 50% or more—without fully spiking insulin in most people with insulin resistance. This minimal fat addition aligns with my approach of using strategic micro-fats to support nutrient uptake while preserving the primary benefits of fasting: autophagy, ketosis, and improved insulin sensitivity.

Is It Still Considered a True Water Fast?

In my methodology outlined in The Metabolic Reset Protocol, an extended water fast prioritizes zero calories for 48-72 hours or longer to reset metabolic pathways. A single tablespoon of oil adds roughly 120 calories and minimal carbohydrates. For complete beginners managing diabetes and blood pressure, this small amount rarely disrupts ketosis or the fasting state if timed correctly—ideally at the same time as your vitamin D dose in the morning.

Research on intermittent fasting and insulin resistance shows that 5-10 grams of pure fat does not elicit a significant insulin response in most middle-aged adults, especially when combined with electrolytes. Avoid mixing with lemon, vinegar, or any carb-containing liquids. Track your blood glucose and ketones for the first few fasts to personalize this. People with joint pain often report better energy and less inflammation when vitamin D levels are optimized this way.

Practical Protocol for Beginners with Insulin Resistance

Start with 2,000-5,000 IU of vitamin D3 paired with one tablespoon of MCT oil or extra-virgin olive oil. Take this once daily during your extended water fast. Stay hydrated with plain water and add electrolytes (sodium 3-5g, potassium 1-2g, magnesium 300-400mg daily) to prevent the common headaches or fatigue that derail many first-timers. This protocol respects your insurance limitations and time constraints—no complex meal plans required.

After the fast, transition using my Metabolic Reset eating windows that emphasize protein and healthy fats to lock in insulin sensitivity gains. Many clients in their late 40s and early 50s who felt overwhelmed by conflicting advice see 8-15 pounds of fat loss in the first month while improving blood pressure and A1C. Always consult your physician before extended fasting, especially with existing medications for diabetes.

Maximizing Results and Avoiding Common Pitfalls

Choose high-quality vitamin D3 supplements that are USP-verified. Pairing with oil helps bypass the absorption issues common in those with gut inflammation from years of failed diets. Monitor for signs of hypercalcemia if taking high doses long-term. In my experience guiding thousands, this simple tweak helps people overcome embarrassment about their weight struggles by delivering measurable metabolic improvements quickly.

💬 What the Community Says

The community shows cautious optimism about adding a tablespoon of oil for vitamin D during extended water fasts when dealing with insulin resistance. Many 45-54 year olds report better energy and stable blood sugar compared to dry supplementation, with several noting 0.2-0.5 mmol/L ketone readings remained consistent. A vocal minority worries it technically breaks a pure water fast and prefer taking D after the fast ends. Those managing diabetes and joint pain frequently share success stories of reduced inflammation but emphasize starting with shorter 24-48 hour fasts first. Beginners often debate MCT versus olive oil, with MCT winning for quicker absorption and less digestive upset. Overall sentiment reflects lived frustration with past diet failures yet growing confidence in personalized fasting tweaks that fit busy middle-income schedules.
Cite this answer
Clark, R. (2026). Can you take vitamin D with a tbsp of oil on an extended water fast for people w. *CFP Weight Loss*. https://ask.cfpweightloss.com/ask/can-you-take-vitamin-d-with-a-tbsp-of-oil-on-an-extended-water-fast-for-people-with-insulin-resistance
Russell Clark, FNP-C, APRN, FNP-C, APRN
About the Author

Russell Clark, FNP-C, APRN, is the founder of CFP Weight Loss in Nashville and CFP Fit Now telehealth. Over 35 years in healthcare — Army Nurse Reserves, Level 1 trauma ER, hospitalist — he developed a 30-week protocol integrating real foods, detox, and low-dose tirzepatide cycling that has helped hundreds of patients lose 30–90 pounds. He and his wife Anne-Marie lost a combined 275 pounds using the same protocol.

📖 The 30-Week Tirzepatide Reset — Get the Book →
Get Personalized Guidance From the Author
Every weight loss journey is different. Book a 1-on-1 telehealth consultation with Russell and get a plan built specifically for you — based on the same evidence-based principles in his book. Available to patients in all 50 states.
Book Your Consultation →
Have a follow-up question?
More Questions 200 answered
▸ The cost of meat is soaring, especially beef. What are y’all doing to stay on budget on a low-carb or ketogenic diet? ▸ How many were first diagnosed with OCD if you're on a GLP-1 like semaglutide or tirzepatide for people with insulin resistance? ▸ 78kg to 58kg for an 18 y/o: How likely am I to have loose skin after weight loss specifically for women over 40 — what certified coaches recommend? ▸ 56M arm day was fun. But arms shrinking from 16 inches to 15 1/2. Gotta up protein? Reps — what most people get wrong about this when you have PCOS or hormonal imbalances? 📖 Lectin-Free Living — Eliminating inflammatory plant proteins that damage the gut lining and trigger the autoimmune responses that often stall… ▸ Crust check 🔥 ribeye done right for long-term maintenance (not just short-term)? ▸ How I Lost 22lbs in 3 Months (155→133lbs at 5'8") after not being able to lose weight for a long time if you're on a GLP-1 like semaglutide or tirzepatide during the weight loss plateau phase? ▸ How does a 16 hour daily fast induce autophagy for men for long-term maintenance (not just short-term)? ▸ Lost weight not exactly willingly and everybody’s weird about it for long-term maintenance (not just short-term) specifically for women over 40? 📖 Anti-Inflammatory Protocol — A way of eating that prioritizes whole foods and eliminates triggers to quiet the internal 'fire' that prevents fat cell… ▸ What is your immediate go to for some relief during ha — what most people get wrong about this — what certified coaches recommend? ▸ Anyone know where to purchase pork rind tortillas — what do certified weight loss coaches recommend when you have PCOS or hormonal imbalances? 📗 The 30-Week Tirzepatide Reset — by Russell Clark, FNP-C, APRN · The complete clinical protocol — 30 weeks of real foods, detox, and low-dose tirzepatide cycling that has helped hundreds of patients lose 3 ▸ How do you deal with traveling when you're on a peptide protocol specifically for women over 40 if you're on a GLP-1 like semaglutide or tirzepatide? ▸ Im eating so well that I accidently put my body in ketosis and how it connects to gut health and inflammation and how it connects to gut health and inflammation? ▸ Were any of you guys fans of Journey? How big were they when you have PCOS or hormonal imbalances? ▸ Do you think they read the responses they receive: how to talk to your doctor about this while doing intermittent fasting? 📖 Bio-Individuality — The understanding that every patient’s metabolic journey is unique, requiring a personalized approach to dosing and diet… ▸ I wanted to ask what is the science behind not allowing any fat during the fat burning phase like how critical is it if I ever had a tiny bit of half-and-half or a tiny bit of olive oil? Is it really do something to the body. ▸ Fitter or kidding myself: how to talk to your doctor about this if you're on a GLP-1 like semaglutide or tirzepatide? ▸ Probiotics worked for a month then stopped. Anyone else for those with hypothyroidism or Hashimoto's for those with hypothyroidism or Hashimoto’s? ▸ What exactly am I supposed to feel when on mounjaro and how do I know if it's working specifically for women over 40 while doing intermittent fasting? ▸ Were any of you guys fans of Journey? How big were they — what the research actually says? 📖 Inflammatory Markers — Clinical indicators like CRP that we monitor to ensure the body is moving from a state of disease to a state of vibrant … 📗 The 30-Week Tirzepatide Reset — by Russell Clark, FNP-C, APRN · The complete clinical protocol — 30 weeks of real foods, detox, and low-dose tirzepatide cycling that has helped hundreds of patients lose 3 ▸ LDN is changing my life, will this last: best practices and common mistakes to avoid for people with insulin resistance? ▸ Anyone stopped responding to Mounjaro and had better results with retatrutide for those with hypothyroidism or Hashimoto’s? ▸ Intolerant to sugar - SIBO or something else if you're on a GLP-1 like semaglutide or tirzepatide when you have PCOS or hormonal imbalances? ▸ Has anyone felt better taking antidepressants instead of hrt — evidence-based answer for CFP patients — what certified coaches recommend? ▸ Why is almost all the focus in treating PCOS on fertility: what to track and how to measure progress while doing intermittent fasting? ▸ How I started this year vs. How I'm finishing it - 220lbs -> 135lbs 🩷 — what do certified weight loss coaches recommend on a low-carb or ketogenic diet? ▸ Can autophagy regenerate muscle during physically active prolonged fast and how it connects to gut health and inflammation and its effect on metabolism and insulin levels? 📖 One Box Protocol — A revolutionary approach where we stretch one 60 mg box of tirzepatide across three metabolic phases, prioritizing long-… ▸ Does mental health predict diabetes as much as BMI? Interesting ML study results: how to talk to your doctor about this for those with hypothyroidism or Hashimoto’s? ▸ Is it normal to lose 6 kg in one week during the weight loss plateau phase for long-term maintenance (not just short-term)? ▸ Is it okay for teenagers to do longterm lowcarb/keto — evidence-based answer for CFP patients for those with hypothyroidism or Hashimoto’s? 📗 The 30-Week Tirzepatide Reset — by Russell Clark, FNP-C, APRN · The complete clinical protocol — 30 weeks of real foods, detox, and low-dose tirzepatide cycling that has helped hundreds of patients lose 3 ▸ Who still goes to steeplechase — what do certified weight loss coaches recommend for long-term maintenance (not just short-term)? ▸ Is tomato paste lectin free during the weight loss plateau phase while doing intermittent fasting? ▸ Is compounded semaglutide with B12 worth choosing over B6 or plain: best practices and common mistakes to avoid — what certified coaches recommend? ▸ How much keto-ade should I safely drink: best practices and common mistakes to avoid and how it connects to gut health and inflammation? 📖 Metabolic Stall — A plateau in weight loss often caused by hidden inflammation or hormonal adaptation, which we break using our specific 7… ▸ I am on my second week of mounjaro (2.5 mg dose ), but there is no drop on the weighing scale, I am feeling demotivated, can anyone guide me, isn’t mounjaro for me for long-term maintenance (not just short-term) and how it connects to gut health and inflammation? ▸ What’s your favorite toothpaste for people with insulin resistance — what the research actually says? ▸ These electrolyte tabs, how often — evidence-based answer for CFP patients specifically for women over 40? ▸ Im eating so well that I accidently put my body in ketosis and how it connects to gut health and inflammation: best practices and common mistakes to avoid? ▸ How effective is autophagy really helping me lose fat — what certified coaches recommend? 📗 The 30-Week Tirzepatide Reset — by Russell Clark, FNP-C, APRN · The complete clinical protocol — 30 weeks of real foods, detox, and low-dose tirzepatide cycling that has helped hundreds of patients lose 3 ▸ What are the scientific ways to promote autophagy on a low-carb or ketogenic diet — what certified coaches recommend? ▸ How do you handle social settings and conversations with other people — what does the research actually say on a low-carb or ketogenic diet? 📖 CICO (Calories In, Calories Out) — An outdated model of weight loss that ignores the role of hormones; we challenge this by focusing on food quality and ho… ▸ What are some things you loved from your childhood that you (virtually) never see/experience anymore during the weight loss plateau phase on a low-carb or ketogenic diet? ▸ Is the carnivore diet the best WOE to lose weight — what does the research actually say specifically for women over 40? ▸ If a random dance partner app existed .. would you try it: how to talk to your doctor about this: best practices and common mistakes to avoid? 📖 Strategic Fat Loading — A critical 48-hour phase at the start of the reset where we prime the body with healthy fats to trigger the transition f… ▸ These electrolyte tabs, how often — evidence-based answer for CFP patients while doing intermittent fasting? ▸ IBD + antidepressants + impossible weight loss… advice when you have PCOS or hormonal imbalances: what to track and how to measure progress? ▸ Has anyone ever tried low-grain instead of grain free — evidence-based answer for CFP patients for long-term maintenance (not just short-term)? 📗 The 30-Week Tirzepatide Reset — by Russell Clark, FNP-C, APRN · The complete clinical protocol — 30 weeks of real foods, detox, and low-dose tirzepatide cycling that has helped hundreds of patients lose 3 ▸ Should I be worried yet, been sitting for 5 days no movement while doing intermittent fasting if you're on a GLP-1 like semaglutide or tirzepatide? ▸ Omnipod. Starting an insulin pump help while doing intermittent fasting for long-term maintenance (not just short-term)? ▸ LDN is changing my life, will this last: best practices and common mistakes to avoid: what to track and how to measure progress? ▸ Got diagnosed today, where do i go from here — what do certified weight loss coaches recommend — what certified coaches recommend?