Obesity rates have skyrocketed in recent decades, with over 40% of adults in the United States now considered obese. This epidemic is associated with a litany of health issues like heart disease, diabetes, and cancer. With fad diets coming and going, many struggle to find a sustainable approach to weight loss. However, one simple but powerful intervention has robust scientific support: intermittent fasting (IF). In this comprehensive guide, you’ll uncover everything you need to know to use IF as a tool to improve your health and lose weight for good.
What is Intermittent Fasting?
Intermittent fasting involves cycling between periods of eating and fasting. It doesn’t specify which foods you should eat, but rather when you should eat them. There are several popular IF approaches:
- 16/8 method: Fast for 16 hours per day and restrict eating to an 8-hour window. This is the most popular and sustainable IF schedule.
- 5:2 diet: Eat normally 5 days per week and limit calories to 500-600 on two non-consecutive days.
- Alternate day fasting: Fast every other day, limiting intake to 500-600 calories on fasting days.
The science behind IF is simple – it allows the body to enter a metabolic state called ketosis, which occurs approximately 8-12 hours after your last meal when glycogen stores become depleted. At this point, the body starts burning stored fat for fuel. Intermittent fasting essentially prolongs this fat burning state by limiting the hours of the day when you eat.
Beyond weight loss, IF may provide other benefits like improved insulin sensitivity, reduced inflammation, better heart health, and protection against conditions like cancer and Alzheimer’s. However, more research is needed on humans to confirm these preliminary findings.
The Art of Fasting
One of the beauties of intermittent fasting is its flexibility. You can choose an IF schedule that aligns with your lifestyle and preferences:
16/8 Method
This entails fasting for 16 hours per day and eating within an 8-hour window. For example, you might eat between 12pm-8pm and fast the other 16 hours. This approach allows for 2 or 3 meals during your eating window. 16/8 is an easy entry into IF that can reap results.
5:2 Diet
Here you pick two non-consecutive days per week to limit intake to 500-600 calories and eat without restriction the other 5 days. Some find it easier to routinely fast on the same 2 days. The 5:2 method may be a tough transition from normal eating but becomes easier over time.
Alternate Day Fasting
This rigorous approach involves severely limiting calories to 500-600 every other day then eating freely on alternating days. Some alternate a 24-hour fast with a feed day. Due to its intensity, the alternate day method may be most suitable for experienced fasters.
When first starting out, begin with more modest fasts of 12-14 hours and work your way up to longer fasts. Give your body time to adjust to using fat for fuel. Transition smoothly by finishing meals a bit earlier each day until you achieve your desired fasting window.
The Science Behind Weight Loss
Intermittent fasting promotes weight and fat loss through several biological mechanisms.
Firstly, it restricts overall calorie intake since you’re limiting eating to a few hours per day or specific days per week. Consuming fewer calories than you’re burning drives weight loss.
Secondly, fasting lowers insulin levels which enables stored fat to be released and burned for energy. Lower insulin also leads to reduced water retention.
Human growth hormone also increases significantly during fasting, by as much as 5 fold. Growth hormone functions to break down fatty acids for energy. Studies show both 24-hour and alternate day fasting boost growth hormone by up to 2000%.
Finally, fasting reduces inflammation and lowers oxidative stress in the body. This creates optimal conditions for fat burning.
Randomized trials comparing intermittent fasting to continuous calorie restriction show similar levels of weight and fat loss. In some studies, IF is even more sustainable long term thanks to the dietary freedom on non-fasting days.
Implementing Intermittent Fasting
Here are some tips to effectively and safely implement intermittent fasting:
- Gradually ease into your desired fasting schedule to allow your body to adapt. This prevents issues like fatigue, headaches, and irritability that can occur initially.
- Drink plenty of water, herbal tea, black coffee and other zero-calorie beverages during fasting periods. This helps curb hunger and prevent dehydration.
- Opt for clean eating during feeding periods by focusing on lean proteins, fruits, vegetables, whole grains, nuts and seeds. Avoid processed foods.
- Try having a fat-burning smoothie or protein shake to break your fast when it’s time to eat. This provides nutrients and energy.
- Schedule fasting periods during busy times of the day so you’re distracted and less likely to think about eating.
- Avoid excessive physical activity during fasts, especially when first starting out. Light walking is generally fine.
- Listen to your body! Stop fasting if you feel unwell and consider a less aggressive method if fasting doesn’t agree with you.
Here are sample meal plans for two popular fasting schedules:
16/8 Sample Meals
12pm Break fast with protein shake
2pm Lunch – grilled chicken salad
5pm Snack – apple and peanut butter
8pm Dinner – salmon with roasted vegetables
5:2 Sample Meals
Fast days:
Breakfast – hardboiled egg (80 cal)
Lunch – tuna salad (200 cal)
Dinner – veggies & hummus (200 cal)
Feed days:
Breakfast – oatmeal and berries
Lunch – turkey sandwich with greens
Dinner – stuffed peppers with quinoa
Safety and Precautions
Intermittent fasting is generally safe for most healthy adults. However, the following groups should consult their healthcare provider before attempting intermittent fasting:
- Those with diabetes or blood sugar regulation issues. Fasting may increase risk of hypoglycemia. Medication adjustments may be required.
- Women who are pregnant or breastfeeding. IF is not recommended as it may be harmful to mom and baby.
- Those with a history of eating disorders. Fasting may exacerbate disordered eating patterns.
- Children and teenagers. IF is not recommended for those still growing and developing.
- Anyone with medical conditions like gastrointestinal issues, nutrient deficiencies, kidney disease, thyroid disorder, and more.
Some side effects like headaches, constipation, and fatigue may occur initially but often improve in a couple weeks as the body adapts. Be sure to break fasts with a healthy meal and stay hydrated to feel your best.
It’s critical to eat a balanced, nutrient-dense diet on non-fasting days. Fasting should not be used to justify eating junk food or binge eating.
Success Strategies
Here are some tips to stick with intermittent fasting and make it work long-term:
- Find an IF schedule that fits your lifestyle. Don’t force a method that’s overly difficult.
- Couple IF with mindful eating of nutritious whole foods when not fasting.
- Stay busy and active to take your mind off eating during fasts. Get quality sleep too.
- Drink water regularly and supplement with electrolytes if needed.
- Avoid constantly obsessing over the scales. Focus on how you look and feel.
- Develop a reward system. For example, enjoy a massage after 2 weeks of consistent fasting.
- Use apps to track fasting times. Connect with motivational fasting communities.
- Be prepared for social occasions that involve food. Don’t be afraid to stick to your schedule.
- Expect setbacks periodically. Get back on track the next day vs giving up entirely.
The Bottom Line
Intermittent fasting provides a simple yet effective approach to weight loss and optimizing health. By restricting eating to set times, you facilitate fat burning and improve numerous biomarkers. With some experimentation, you can discover an IF method that suits your needs and leaves you feeling energized. Approach intermittent fasting with realistic expectations. Be patient and stick with it to unlock its many benefits. Ready to get started? Sign up for my free Intermittent Fasting Guidebook using the form below!
Thank you for reading this post, don't forget to subscribe to our free newsletter
!
