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.
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.

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
Good calorie amount? Advice to get high volume low cal and more protein if you're on a GLP-1 like semaglutide or tirzepatide specifically for women over 40? Depressive symptoms from non-stick air fryer — what do certified weight loss coaches recommend if you're on a GLP-1 like semaglutide or tirzepatide? Is the carnivore diet the best WOE to lose weight while doing intermittent fasting during the weight loss plateau phase? When Someone Paid by Credit Card, We Had to Drag Out This — what most people get wrong about this and how it connects to gut health and inflammation? Not a whingeing post. Just looking for some guidance.. I started IF with great success. I felt energised & found making note of the fasting stages really motivational. I had a break from IF: how to talk to your doctor about this for people with insulin resistance? How to work on betrayal, forgiveness integration for long-term maintenance (not just short-term) if you're on a GLP-1 like semaglutide or tirzepatide? What is the connection between I reduced my IR from 15.5 to 4 in 3 months if you're on a GLP-1 like semaglutide or tirzepatide? 📖 Adipose Tissue Signaling — The way fat cells communicate with the brain; our goal is to fix these signals so the body stops defending an unnaturall… How I cured my bad breath. Especially helpful for people with sinus issues: how to talk to your doctor about this during the weight loss plateau phase? 📗 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 Here's the things I wish I'd known back then... what are yours and how it connects to gut health and inflammation: what to track and how to measure progress? What's your pre-show drug of choice these days and its effect on metabolism and insulin levels and its effect on metabolism and insulin levels? How did I not get a heads up? I now make it my goal to help, support and inform others heading towards menooause and its effect on metabolism and insulin levels — what certified coaches recommend? Have you switched from Semaglutide to Tirzapatide? How was it: best practices and common mistakes to avoid specifically for women over 40? 📖 Metabolic Reset — The process of retraining your body to utilize stored fat for fuel and regulating hunger hormones so you can maintain yo… Do you know of any snacks that you can just chew on when you're bored on a low-carb or ketogenic diet — what certified coaches recommend? Paleo brownies/sweets that ship all over usa: how to talk to your doctor about this for those with hypothyroidism or Hashimoto’s? Refreshing Summer snack ideas during the weight loss plateau phase: what to track and how to measure progress? Is there anyone who drink coffee after fatty carnivore meal — how a functional medicine approach differs and its effect on metabolism and insulin levels? 📗 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 Can you take beta blockers and GLP-1s together: best practices and common mistakes to avoid and its effect on metabolism and insulin levels? Diabetics with TPN (IV nutrition experience) on a low-carb or ketogenic diet and how it connects to gut health and inflammation? 📖 One Box Protocol — A revolutionary approach where we stretch one 60 mg box of tirzepatide across three metabolic phases, prioritizing long-… Carbs are important for muscle growth… but what if I’m insulin resistant and how it connects to gut health and inflammation: best practices and common mistakes to avoid? Gaining tons of weight but normal levels — what does the research actually say for people with insulin resistance? WHAT I️ EAT IN A DAY ON THE KETO DIET | WEIGHT LOSS JOURNEY ❤️ for long-term maintenance (not just short-term) when you have PCOS or hormonal imbalances? 📖 Maintenance Phase — The final 28 days of our 70-day cycle where we stabilize the new weight and solidify the metabolic habits that prevent f… My friends stopped being impressed by my weight loss ages ago. I just reached my goal weight, would you cheer for me in their place: what to track and how to measure progress when you have PCOS or hormonal imbalances? Does anyone else remember the darkest time of our Generation — evidence-based answer for CFP patients — what certified coaches recommend? Why is this ruining my life? Doctor's don't take me seriously. 20 year old male: best practices and common mistakes to avoid 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 I’m looking into possibly going grain free and I was wondering if it was just as healthy as doing keto or paleo — what most people get wrong about this and how it connects to gut health and inflammation? 📖 Muscle Sarcopenia — The dangerous loss of lean muscle mass often seen in traditional 'crash diets' or high-dose GLP-1 use, which we combat t… What a month of paleo has done for me while doing intermittent fasting and its effect on metabolism and insulin levels? Being underweight, panic and anxiety. Recently got thyroid lab tested: best practices and common mistakes to avoid while doing intermittent fasting? How did you stop your health anxiety — what do certified weight loss coaches recommend specifically for women over 40? How the heck do people with health anxiety handle anxiety med side effects: what to track and how to measure progress for people with insulin resistance? Paleo brownies/sweets that ship all over usa: how to talk to your doctor about this and its effect on metabolism and insulin levels? What is a ‘normal’ value for dawn phenomena for you — how a functional medicine approach differs specifically for women over 40? 📖 Nutrient Density — Prioritizing foods that provide maximum vitamins and minerals per calorie to satisfy the brain and end the cycle of hidd… When period stopped did you feel like the worst pmdd of all time daily or while doing intermittent fasting? 📗 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 My stomach is killing me, any advice if you're on a GLP-1 like semaglutide or tirzepatide and its effect on metabolism and insulin levels? When you get your microdose calculations wrong for the Monday morning meeting for people with insulin resistance if you're on a GLP-1 like semaglutide or tirzepatide? Good calorie amount? Advice to get high volume low cal and more protein if you're on a GLP-1 like semaglutide or tirzepatide: what to track and how to measure progress? Been going out with this girl and I think it’s destroyed my microbiome for people with insulin resistance when you have PCOS or hormonal imbalances? 📖 Tirzepatide — A dual-acting medication targeting both GLP-1 and GIP receptors, providing a more comprehensive metabolic signal than si… Has anyone stopped HRT and then restarted it for people with insulin resistance — what certified coaches recommend? For those who took metformin, how soon did you see benefits: best practices and common mistakes to avoid during the weight loss plateau phase? Dark(ish) areas for stargazing during the weight loss plateau phase for long-term maintenance (not just short-term)? Will doing omad 2-3 times a week get rid of it or reduce loose skin? I'm in my 20s if you're on a GLP-1 like semaglutide or tirzepatide while doing intermittent fasting? 📗 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 Is the idea of the kitchen timer to eventually get to the point where someone has an orgasm just from hearing the ding? Pavlov's orgasm and the role of cortisol and stress hormones while doing intermittent fasting? After losing weight, does it feel like you could do anything — evidence-based answer for CFP patients during the weight loss plateau phase? Any of you low carb, low to no fruits people go camping? Even if not, what are you eating and how it connects to gut health and inflammation while doing intermittent fasting? 📖 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… Gaining tons of weight but normal levels — what does the research actually say while doing intermittent fasting? Can sugar free candy make a difference and how it connects to gut health and inflammation: what to track and how to measure progress? How much keto-ade should I safely drink — how a functional medicine approach differs and how it connects to gut health and inflammation? 📖 30-Week Tirzepatide Reset — Our signature protocol using a single 60 mg box of medication cycled over 30 weeks to achieve lasting metabolic transfor… “You shouldn’t feel anything” while doing intermittent fasting specifically for women over 40? How long was your withdrawal when you went sugarfree if you're on a GLP-1 like semaglutide or tirzepatide — 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 How I cured my bad breath. Especially helpful for people with sinus issues: what to track and how to measure progress: what to track and how to measure progress? How to get better cholesterol test scores during the weight loss plateau phase if you're on a GLP-1 like semaglutide or tirzepatide?