Expert Q&A

Anyone want to join me in a 90 day keto/fasting/workout challenge: best practices and common mistakes to avoid

Why a 90-Day Keto Fasting Workout Challenge Works for Beginners Over 45

I’ve guided thousands through structured challenges that deliver real results without the rebound. A 90-day keto fasting workout challenge combines ketosis, intermittent fasting, and progressive movement to reset metabolism, especially when hormonal changes make weight loss feel impossible. For those managing diabetes and blood pressure, this approach can improve insulin sensitivity within weeks when done correctly. The key is sustainability—our method focuses on 16:8 fasting windows, moderate keto macros (70% fat, 20% protein, 10% carbs), and joint-friendly workouts that fit busy middle-income schedules.

Best Practices for Your 90-Day Challenge

Start with a 7-day prep phase: track baseline blood glucose, ketones (aim for 0.5–3.0 mmol/L), and body measurements rather than scale weight alone. During the challenge, maintain a 16:8 intermittent fasting window—eat between 12pm and 8pm to align with circadian rhythms and reduce joint inflammation. Keto macros should target 20–30g net carbs daily from leafy greens and cruciferous vegetables. For workouts, follow my 3x weekly “Joint-Safe Circuit”: 20 minutes resistance bands, 15 minutes brisk walking, and 10 minutes yoga flows. This burns 400–600 calories per session while protecting knees and back. Hydrate with 3–4 liters of water plus electrolytes (4g sodium, 1g potassium daily) to prevent keto flu. Weekly check-ins measuring fasting blood sugar help those with diabetes track improvements without insurance-covered programs.

Common Mistakes That Derail Progress

Many fail by jumping into 20:4 fasting too soon, triggering cortisol spikes that worsen hormonal weight gain. Another pitfall is “dirty keto”—relying on processed meats instead of whole foods, which stalls fat loss after week four. Over-exercising on low calories leads to burnout; limit HIIT to once weekly. Ignoring sleep (under 7 hours) sabotages results because growth hormone release during deep sleep is critical for preserving muscle in your 40s and 50s. Finally, quitting at the first plateau around day 21 is common—our data shows pushing through with adjusted calories (add 200 healthy fats) often restarts loss by day 28.

How to Track Success and Stay Consistent

Use a simple app to log meals, fasting times, and workouts—no complex plans required. Celebrate non-scale victories like lower blood pressure readings (many see 10–15 mmHg drops) and reduced joint pain. By day 90, participants following these guidelines lose 12–25 pounds while improving energy and confidence. Ready to transform without another failed diet? My book *Sustainable Fat Loss After 40* expands on these protocols with meal templates and troubleshooting guides. Start your challenge today with one small commitment: your first 16-hour fast tomorrow.

💬 What the Community Says

Participants in online forums are cautiously optimistic about 90-day keto fasting workout challenges but emphasize the need for modifications after 45. Many share stories of losing 15–20 pounds while improving blood sugar, yet a vocal group warns about severe keto flu, muscle cramps, and hair loss when electrolytes are neglected. Beginners with joint pain appreciate low-impact recommendations but debate fasting windows—some thrive on 16:8 while others report fatigue and stalled progress on longer fasts. Insurance and cost concerns surface frequently, with users seeking affordable home-based alternatives to paid programs. Common debates center on sustainability versus rapid results; most agree that strict adherence works short-term but many regain weight without gradual carb reintroduction. Lived experiences highlight hormonal frustration in perimenopausal women and the relief of finding simple routines that fit around full-time jobs. Overall, the community values practical advice that acknowledges real-life barriers over extreme transformations.
Clark, R. (2026). Anyone want to join me in a 90 day keto/fasting/workout challenge: best practice. *CFP Weight Loss*. https://ask.cfpweightloss.com/ask/anyone-want-to-join-me-in-a-90-day-keto-fasting-workout-challenge-best-practices-and-common-mistakes-to-avoid
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
What are some things you loved from your childhood that you (virtually) never see/experience anymore during the weight loss plateau phase and how it connects to gut health and inflammation? Metformin (6 weeks in) for insulin resistance — can the gut stuff actually get better during the weight loss plateau phase? How to incorporate psyllium husk with intermittent fasting — what do certified weight loss coaches recommend while doing intermittent fasting? Does autophogy start sooner if following a keto diet before a fast and the role of cortisol and stress hormones: best practices and common mistakes to avoid? How to incorporate psyllium husk with intermittent fasting — what do certified weight loss coaches recommend if you're on a GLP-1 like semaglutide or tirzepatide? 📖 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… Can you tell a difference in my face — how a functional medicine approach differs specifically for women over 40? What is a ‘normal’ value for dawn phenomena for you for people with insulin resistance for those with hypothyroidism or Hashimoto’s? Should Endotoxin be the norm from vendors along with COA’s and how it connects to gut health and inflammation: best practices and common mistakes to avoid? 📗 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 Making me super tired and in a dreamy, chill, ready for a nap state for most of the day and its effect on metabolism and insulin levels — what the research actually says? Insulin resistance caused my weight gain despite eating low calorie diet, anyone else when you have PCOS or hormonal imbalances — what the research actually says? Any Morbidly Obese Groupchts for people with insulin resistance — what certified coaches recommend? 📖 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… Why is almost all the focus in treating PCOS on fertility: what to track and how to measure progress specifically for women over 40? Does anyone here successfully cheat without going completely off the rails: how to talk to your doctor about this for people with insulin resistance? Who still goes to steeplechase — what do certified weight loss coaches recommend when you have PCOS or hormonal imbalances? What is your immediate go to for some relief during ha — what most people get wrong about this and its effect on metabolism and insulin levels? Probiotics worked for a month then stopped. Anyone else for those with hypothyroidism or Hashimoto's while doing intermittent fasting? Oval twice a week patch - what was I using on a low-carb or ketogenic diet and how it connects to gut health and inflammation? 📗 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 can I gain 10kg on Paleo when you have PCOS or hormonal imbalances? 📖 Amylopectin A — The specific starch found in modern wheat that causes rapid, dangerous spikes in blood glucose and promotes belly fat st… Can i Fast for autophagy for loose skin without losing anymore weight — how a functional medicine approach differs for long-term maintenance (not just short-term)? Probiotics worked for a month then stopped. Anyone else for those with hypothyroidism or Hashimoto's if you're on a GLP-1 like semaglutide or tirzepatide? Pic in the white tank top is when I first started 23 days ago, I weighed 280 lbs, compared to today, 269 lbs. I have been dieting and working out frequently, can you even see a difference: how to talk to your doctor about this when you have PCOS or hormonal imbalances? IBD + antidepressants + impossible weight loss… advice when you have PCOS or hormonal imbalances and its effect on metabolism and insulin levels? Does salt instantly relieve a slight headache for you if you're on a GLP-1 like semaglutide or tirzepatide for people with insulin resistance? 📖 Nutrient Density — Prioritizing foods that provide maximum vitamins and minerals per calorie to satisfy the brain and end the cycle of hidd… Has anybody heard of or experienced improvement from neurological disorders through fasting and autophagy if you're on a GLP-1 like semaglutide or tirzepatide — what certified coaches recommend? 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? What foods to stock for overnight guest — evidence-based answer for CFP patients for people with insulin resistance? 📗 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 and its effect on metabolism and insulin levels? 📖 30-Week Tirzepatide Reset — Our signature protocol using a single 60 mg box of medication cycled over 30 weeks to achieve lasting metabolic transfor… What is your intermittent fasting schedule, what results are you seeing, and are you happy with it and its effect on metabolism and insulin levels when you have PCOS or hormonal imbalances? What actually helps with the dryness when you have PCOS or hormonal imbalances if you're on a GLP-1 like semaglutide or tirzepatide? How long until I start losing weight this way — how a functional medicine approach differs: best practices and common mistakes to avoid? Why aren’t obesity medical breakthroughs a bigger deal and its effect on metabolism and insulin levels for long-term maintenance (not just short-term)? Why is my psychiatrist recommending supplements — how a functional medicine approach differs and its effect on metabolism and insulin levels? How many were first diagnosed with OCD for long-term maintenance (not just short-term) during the weight loss plateau phase? HOW TO DO AN AGGRESSIVE CUT WITH A STRESSFUL LIFESTYLE on a low-carb or ketogenic diet: best practices and common mistakes to avoid? 📖 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… 📗 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 For those who've lost the weight and kept it off... did you ever achieve true food freedom on a low-carb or ketogenic diet during the weight loss plateau phase? Probiotics worked for a month then stopped. Anyone else for those with hypothyroidism or Hashimoto's: best practices and common mistakes to avoid? What lifestyle changes are your golden rule for reversing IR during the weight loss plateau phase for those with hypothyroidism or Hashimoto’s? What is your immediate go to for some relief during ha — what most people get wrong about this if you're on a GLP-1 like semaglutide or tirzepatide? Has anyone felt better taking antidepressants instead of hrt — evidence-based answer for CFP patients: what to track and how to measure progress? 📖 Smart Cycling — The strategic alternating of medication doses with planned 'off' periods to prevent receptor desensitization and ensure … How do you handle social settings and conversations with other people — what does the research actually say: best practices and common mistakes to avoid? Those of you with Reta experience how does this protocol look for people with insulin resistance on a low-carb or ketogenic diet? Is it normal to feel unhappy during weight loss when you have PCOS or hormonal imbalances while doing intermittent fasting? Why is my psychiatrist recommending supplements — how a functional medicine approach differs if you're on a GLP-1 like semaglutide or tirzepatide? Are people who get no effect just using bad product: best practices and common mistakes to avoid: what to track and how to measure progress? 📗 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 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) while doing intermittent fasting? I sometimes feel like people only talk about the obvious symptoms like irregular periods or weight gain, but the fatigue can be just as overwhelming. Has anyone else felt completely drained even: how to talk to your doctor about this: what to track and how to measure progress? 📖 Bio-Individuality — The understanding that every patient’s metabolic journey is unique, requiring a personalized approach to dosing and diet… Are people who get no effect just using bad product: best practices and common mistakes to avoid: best practices and common mistakes to avoid? IBD + antidepressants + impossible weight loss… advice when you have PCOS or hormonal imbalances — what certified coaches recommend? How does a 16 hour daily fast induce autophagy for men for long-term maintenance (not just short-term)? Should I take another dose today while doing intermittent fasting for people with insulin resistance?