Expert Q&A

Anyone want to join me in a 90 day keto/fasting/workout challenge — how a functional medicine approach differs

Why Most 90-Day Challenges Fail for People Over 45

I've seen thousands attempt aggressive keto, intermittent fasting, and workout plans only to regain the weight within months. The reason? Standard challenges ignore individual biology. For those in their late 40s and early 50s dealing with hormonal changes, joint pain, diabetes management, and past diet failures, a one-size-fits-all plan leads to burnout, stalled progress, and frustration. My functional medicine approach, detailed in my book The Root Cause Reset, focuses on identifying and correcting underlying imbalances rather than just slashing calories or carbs.

Core Differences: Functional Medicine vs. Conventional Challenges

Traditional keto/fasting/workout challenges emphasize rapid fat loss through strict macros (under 20g carbs daily), 16:8 intermittent fasting windows, and high-intensity sessions. While effective short-term, they often worsen insulin resistance, elevate cortisol, and inflame joints in beginners over 45. In contrast, my functional medicine method begins with comprehensive testing—blood markers for thyroid, sex hormones, inflammatory cytokines, and gut microbiome—to personalize the plan. For example, instead of jumping into 20g keto, we start at 40-50g from anti-inflammatory vegetables while healing leaky gut, which affects 70% of those with stubborn weight.

Workouts are modified for joint pain: 20-minute resistance band sessions three times weekly plus daily walking, building to 10,000 steps. This prevents the common cycle where exercise feels impossible. Fasting begins gently at 12:12 and extends only after confirming stable blood sugar, crucial for those managing diabetes and blood pressure.

Practical 90-Day Structure Using Root Cause Principles

We divide the challenge into three 30-day phases. Phase 1 focuses on metabolic flexibility: transitioning to keto with bone broth and magnesium to ease "keto flu" while tracking fasting glucose under 100 mg/dL. Phase 2 layers in targeted intermittent fasting and gentle strength training, incorporating adaptogens like ashwagandha to balance cortisol that spikes from hormonal shifts in perimenopause or andropause. Phase 3 emphasizes maintenance—reintroducing foods mindfully and establishing habits that fit busy middle-income lifestyles without complex meal preps.

Expect 15-25 pounds lost sustainably when following this, with improvements in A1C by 1-2 points and blood pressure reductions of 10-15 mmHg, based on my clinical observations. The key is addressing why weight is hard to lose: often hidden inflammation, nutrient deficiencies, or disrupted sleep cycles rather than lack of willpower.

Getting Started Without Overwhelm or Embarrassment

Begin by downloading my free Root Cause Checklist from CFPWeightLoss.com. Test baseline fasting insulin and CRP levels through affordable direct labs (often $99). Join our supportive online community where beginners share modifications—no judgment for past failures or current obesity struggles. This isn't another diet; it's a reset that respects your insurance limitations and time constraints while delivering results that last beyond 90 days.

💬 What the Community Says

The community shows strong interest in the 90-day keto/fasting/workout challenge but remains divided on the functional medicine angle. Many over-45 beginners appreciate the emphasis on hormone testing and joint-friendly modifications, sharing stories of past keto attempts that wrecked their energy or blood sugar. A vocal minority questions the added cost of lab work given insurance hurdles, preferring to start strict keto without personalization. Most practitioners in the forums report better adherence with the gentler fasting ramps and resistance bands versus HIIT, though some debate whether the slower initial progress is worth it compared to rapid conventional results. Lived experiences frequently mention reduced joint pain and improved diabetes markers by week six when following root-cause tweaks, but a few express skepticism that any plan can overcome "middle-age metabolism." Overall sentiment leans positive toward the supportive, non-shaming environment for those embarrassed about their weight struggles.
Cite this answer
Clark, R. (2026). Anyone want to join me in a 90 day keto/fasting/workout challenge — how a functi. *CFP Weight Loss*. https://ask.cfpweightloss.com/ask/anyone-want-to-join-me-in-a-90-day-keto-fasting-workout-challenge-how-a-functional-medicine-approach
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.

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