7 Intermittent Fasting Mistakes (and How to Avoid Them)

When I first heard about intermittent fasting, I thought you had to go all out. Skip breakfast, survive on coffee, push yourself through the morning until lunch, and call it “healthy.” Sound familiar?

Well… that’s mistake number one. And the truth is, I see people making the same handful of mistakes with fasting over and over. And it’s not because they’re lazy or undisciplined. It’s usually because we’ve been sold a one-size-fits-all fasting plan that doesn’t actually work for most of us.

But once you know these pitfalls, fasting becomes a whole lot easier and way more effective for your energy, blood sugar, skin, digestion, and even longevity.

In today’s post, I’ll go over the seven most common intermittent fasting mistakes I see (and how you can avoid them).

? Before we dive in, make sure to grab access to my Free Wellness Library. It’s packed with e-books, gut health checklists, food trackers, and practical resources to help you feel better faster. You can get your free access below!

7 Most Common Intermittent Fasting Mistakes

If you’ve been curious about fasting but aren’t quite sure why it feels harder than it should, you’re not alone. A few simple missteps can make the whole process more draining than energizing.

So, let’s clear those up.

1. You Need a 16-Hour Fast Every Day

There’s a big push right now for the 16:8 fasting style. For a small slice of the population (mainly men aged 25–45), that works great. But for most people? Not so much.

The sweet spot is usually 10–12 hours overnight. That’s long enough to give your body the benefits of fasting without pushing it too far.

Tip: Stop eating after dinner. Brush your teeth, close the kitchen, and let your body do its job while you rest.

Related:
How to Fast Smarter for Your Unique Dosha Body Type

2. Not Staying Hydrated During a Fast

When you’re not eating food, you’re also not getting water from fruits or veggies. That’s why headaches, fatigue, or “hanger” can hit hard. Often, you’re just dehydrated.

Try this simple upgrade:

• Squeeze lemon or lime into water.
• Add a tiny pinch of Himalayan or Real Salt (from Utah salt beds).

It’s like a natural Gatorade without breaking your fast.

3. Overdoing Caffeine in the Morning

A black coffee in the morning is often labeled “fasting-friendly.” And technically, yes.

But there’s a catch: caffeine spikes adrenaline and cortisol. That puts you in a more catabolic state, meaning you’re breaking down muscle tissue instead of protecting it.

This is especially rough on people who already run on higher stress hormones (think: naturally lean, higher-energy types).

If you love your coffee, just keep it in check. One cup is fine, just don’t rely on it to carry you through a fasted morning.

4. Overeating at One Big Meal

Some people fast all day, then pack everything into one giant dinner. The problem is that refeeding after restriction can raise IGF-1.

In a 2010 mouse study, intermittent fasting with refeeding led to ~48% higher IGF-1 compared to normal feeding.¹ While tumor size didn’t differ in that study, other research has linked elevated IGF-1 levels to greater cancer risk.

So while one big meal may seem convenient, spreading calories more evenly may better support long-term health.

? Enjoying this post? Find more helpful resources in the Free Wellness Library, including e-books, checklists, trackers, and more!

5. Believing More Fasting Days = Better Results

When you start fasting, feel amazing, and think “if some is good, more must be better.” Not true.

The best place to start is simple:

• Do a 12-hour overnight fast (7 pm dinner → 7 am breakfast).
• Once you’re comfortable, try a 24-hour fast once a month.
• Maybe build up to once a week if your body tolerates it.

Slow and steady really does win here. Jumping straight into multiple 24-hour fasts a week is a recipe for burnout.

Related:
How to Do Intermittent Fasting in 24 Hours (Without Feeling Miserable)

6. Doing Intense Workouts

Pushing through hard workouts on a fast, especially in the beginning, often leaves people dizzy, drained, and discouraged.

Instead, think of fasting days as “light movement” days: go for a walk, do some yoga, or even treat yourself to an infrared sauna.

Once your body adapts, you can experiment with workouts during fasts, but don’t start there.

7. Applying Long, Low-Carb Fasts to Everyone

Long, low-carb fasting works better for men than for women. Women’s bodies are especially sensitive to calorie and carb restriction because of their impact on hormones.

Here’s what the research shows:

• Reproductive hormones respond quickly to energy deficits. Even just a few days of low energy availability can suppress LH (luteinizing hormone) pulsatility in women, one of the earliest signs of menstrual disruption.²
• Thyroid function can slow down. Caloric restriction is known to lower circulating T3 (active thyroid hormone), reflecting a “metabolic slowdown” during restriction.³
• Hunger hormones shift. Dieting and weight loss consistently lower leptin and increase ghrelin, which can drive more hunger and, in some cases, binge-like eating.⁴
• Sex-specific differences are real. In one study, alternate-day fasting impaired glucose tolerance in women but not in men, suggesting that women’s metabolism is more vulnerable under fasting stress.⁵

So while men often tolerate long, low-carb fasts better, women should be more cautious. A daily 12-hour overnight fast is generally safe, while longer fasts should be used sparingly, and always with an eye on energy, cycles, and overall health.

Quick Recap

✅ A 10–12 hour overnight fast is enough for most people
✅ Stay hydrated—add lemon/lime + pinch of salt
✅ Watch the caffeine (don’t overdo it)
✅ Don’t make up for fasting with one huge meal
✅ More fasting days ≠ better
✅ Save intense workouts for non-fasting days (at first)
✅ Women should stick with a gentler fasting approach

Final Thoughts

Fasting can be life-changing, but only if it’s done in a way that supports your body, not stresses it. Start small, give yourself grace, and remember that health is about feeling good inside and out, not just hitting a certain fasting window or scale number.

Now, I’d love to hear from you! Which of these intermittent fasting mistakes have you caught yourself making? Drop a comment and let’s chat about it.

Additional Resources

• 10 Proven Health Benefits of Intermittent Fasting You Should Know
• How to Do Intermittent Fasting in 24 Hours (Without Feeling Miserable)
• Why 4:3 Intermittent Fasting Works Better Than Dieting
• Why Skipping Dinner Works Better on a 16:8 Fasting Plan
• The Best 16:8 Intermittent Fasting Schedule (Hint: It’s Not 12–8)

Footnote:

1. Effect of intermittent fasting on prostate cancer tumor growth in a
   mouse model ↩︎
2. Luteinizing hormone pulsatility is disrupted at a threshold of energy availability in regularly menstruating women ↩︎
3. Triiodothyronine and leptin repletion in humans similarly reverse weight-loss-induced changes in skeletal muscle ↩︎
4. Long-Term Persistence of Hormonal Adaptations to Weight Loss ↩︎
5. Alternate-day fasting in nonobese subjects: effects on body weight, body composition, and energy metabolism ↩︎

? Like this and want to save it for later? Tap the Pinterest Pin button below—it’s an easy way to keep it on hand when you need it.

Join the community and gain instant access to

our free wellness library of e-books, worksheets, and resources.

SEND IT MY WAY!

Built with Kit