Should I be fasting or feeding? When, Why & How. The body works in rhythms, so we create "fasting" windows and we create "feeding" windows. 16:8 (Feeding or eating in an 8 hour window & fasting or zero calories for 16 hours) works at first because it stimulates fat-burning hormones. But when it’s done every day for too long especially in women your body eventually adapts by slowing your metabolism, conserving energy, and holding onto fat. So if fat loss has stalled, energy feels lower, or your body feels “flat”, it’s not willpower. It’s biology. 1. Why does 16:8 Work at First? When you fast, your body releases- - Adrenaline - Norepinephrine - Fatty acids These hormones- - Increase fat burning - Keep metabolism from dropping - Make you feel sharp, light, focused That’s why 16:8 often feels amazing at first. But that effect is meant to be temporary. Fasting is a stress signal. Stress is helpful only when followed by recovery. If your body thinks a Tiger is chasing it, there's no way it will release fuel (Fat) 2. Why Daily 16:8 Eventually Stops Working When fasting happens every single day, the body stops seeing it as a helpful pulse and starts seeing it as a pattern of scarcity. At that point your body says, “Food is predictably limited. I should conserve energy.” So it responds by - - Lowering resting metabolic rate - Burning fewer calories at rest - Losing some muscle - Increasing adaptive thermogenesis (energy conservation) This can happen in 2-3 weeks, not years. So you may be - - Eating less - Fasting more - Working harder - and yet burning less. That’s not failure. That’s your metabolism doing its job. 3. Why Shorter Windows Can Burn More Fat A 12:12 or 14:10 window does not turn fat loss off. You still get the following benefits - - Insulin drops overnight - Fat mobilization in the morning - Access to stored fat - Better thyroid signaling - Better leptin (fat-loss hormone) signaling - Better muscle protection - Better recovery between stress pulses

In simple terms, Synthroid (levothyroxine) gives your body T4. T4 is not the really active thyroid hormone. Your body still has to turn T4 into T3 for it to actually raise metabolism, support fat loss, and improve energy. That conversion step matters more than most women are ever told. When your body is calm, nourished, and rested, T4 tends to convert into T3. When your body is - under stress, - inflamed, - under-fed, - over-trained, - or under-slept, it often converts T4 into reverse T3 instead. Reverse T3 is an inactive form of thyroid hormone. It blocks thyroid receptors and slows metabolism inside the cells. So even though your blood work might show normal or even high thyroid hormone levels, your cells can still be functionally hypothyroid. FitnHealthy Forever Tip - This is why we recommend asking for complete Thyroid testing including 1. TSH 2. T4 3. T3 4. Reverse T3 5. Free T4 6. Free T3 7. T3 Uptake/TBG 8. Thyroid Peroxidase (TPO) Antibodies 9. Thyroglobulin (Tg) Antibodies This creates a frustrating pattern. You are “on thyroid medication,” but you still feel tired, foggy, cold, or stuck. Fat loss stalls. Energy does not improve the way you expected. Menopause symptoms like sleep disruption, anxiety, hot flashes, or heart racing can persist or worsen. At the same time, having higher circulating thyroid hormone still increases stress signaling, cortisol, nervous system activation, and bone turnover. So your body gets the stress side of thyroid hormone without getting the metabolic benefit. That is why you can feel wired but tired at the same time. That is also why fat loss can stall even when labs look fine. This is not because your body is broken. It is because your body is trying to protect you. Under stress, the body shifts into a conservation and survival mode. It blocks metabolism to preserve energy, holds onto fat to protect you, and prioritizes immediate survival over long-term goals like fat loss or rebuilding tissue.