Three meals a day and healthy snacks are how many achieve optimum health.
However, some believe that manipulating the time you eat and how much you eat offers additional health benefits. This eating strategy is intermittent fasting (IMF).
This article reviews IMF so you can decide if it’s the right fit for you.
WHAT IS INTERMITTENT FASTING?
Intermittent Fasting is an eating strategy that fluctuates between energy restriction and normal calorie intake over designated time spans.
IMF is not deprivation, starvation or one-size-fits-all. There are various styles of IMF that fit different lifestyles.
TYPES OF IMF:
- Alternate Day Fasting: 24 hour periods of consuming zero calories followed by days of eating and drinking normally (1).
- Modified Fasting or Whole Day Fasting: The most common form of this type is the 5:2 diet. In this fast, people consume about 20-25% of their calories on two nonconsecutive days and eat normally the other five days of the week (1).
- Time-Restricted Fasting: This form of fasting allows individuals to eat whatever they’d like, just in a limited amount of time during the day. It ranges from a 3 to 12 hour eating window. Fasting occurs during the rest of the day or over night (1).
SUMMARY: INTERMITTENT FASTING IS A FLEXIBLE DIET STRATEGY IMPACTING THE TIMESPAN AND AMOUNT OF EATING. THERE ARE A VARIETY OF IMF REGIMENS.
WHAT’S THE HYPE AROUND IMF?
Proposed health effects of IMF are vast and varied.
Fastings’ premise is that it allows the body to repair, replenish, and recycle cells involved in metabolism. Think of it as a “metabolic tune-up.”
Many processes during this this tune-up remain a mystery. However, a predominant theory is that the body utilizes ketone bodies as an alternative fuel source to glucose during fasting. These ketones act as a potent energy source, providing fuel to high-demand areas such as brain neurons(2).
Additional benefits of fasting come from its ability to reduce total calorie intake. It’s well established that eating less helps support longevity and the risk of many chronic diseases (3).
SOME OF THE POTENTIAL EFFECTS OF IMF INCLUDE:
- Slowing of tumor growth (in mice at the current moment) (4)
- Assisting in weight loss (5)
- Links eating to circadian rhythms (1)
- Enhancing metabolic health (5)
- Improving lipid biomarkers (1)
- Decreasing inflammation (1, 6)
- Improving cognition (7)
- Improving glucose regulation (8)
- Changes in the gut microbiome for improved digestive function (1)
Most IMF studies are on animals, not humans. While small scale human trials are promising, further research is needed before any strong conclusions can be made (9).
SUMMARY: THE POTENTIAL HEALTH BENEFITS OF IMF ARE GREAT AND IMPACT MANY ASPECTS OF WELLBEING SUCH AS HEART HEALTH, BRAIN FUNCTION, METABOLISM, AND HORMONE CONTROL. THE EXACT MECHANISM OF THE BENEFITS IS STILL UNCLEAR.
WHO SHOULD TRY INTERMITTENT FASTING?
IMF is appropriate for anyone without pre-existing medical conditions, in good health, looking to experiment with their diet in a safe and reasonable manner.
People who are in developmental life stages such as pregnancy or early childhood or who are critically or chronically ill should not try IMF. The potential harm is unknown as it hasn’t been studied in these populations (12).
SUMMARY: FASTING IS BEST FOR THOSE IN GOOD HEALTH AND CAN POTENTIALLY BE USED AS A WEIGHT MANAGEMENT STRATEGY.
HOW CAN I GET STARTED WITH IMF?
You want to give IMF a try?
Here is a step-by-step guide on how to get started.
- Decide which style of fasting is right for you. In my opinion, the time restricted fast and the modified fast are the easiest, safest, and most manageable options to incorporate into daily living.
- Plan out your week. The key to sticking to a fasting schedule is planning. Decide what days you will fast based on your work schedule, exercise regimen, weekend plans, etc.
- Implement the fast. Everyone reacts to fasting differently, but after a week or two, evaluate how you did, how you feel, and how you liked it. There is no set amount of adjustment time as everyone’s body reacts differently.
- Adjust your fast to meet your needs. There is no specific amount of weeks or years to practice IMF. Currently, the long-term benefits or harms of fasting are not fully known.
COMMON CHALLENGES OF IMF:
- Can I fast if I have an active lifestyle?
- Yes, but planning is key. Because your fasting days aren’t consecutive, plan workouts around your fast days. You can also try a low intensity workout during fasting periods.
- Additionally, if you plan to do an morning cardio workout on your fasting day, fill up with complex carbohydrates the night before to ensure you will have glycogen stores to use for energy.
- What should I do if I’m hungry on fasting days?
- Hunger is common when you initially adjust to IMF. It’s essential to stay hydrated! Water consumption is allowed and encouraged during fasts. Consider sipping broths, vegetable soups, herbal teas, black coffee, seltzers, and stevia sweetened zero calorie beverages as a great low calorie beverage option.
- For a small burst of energy with little calories, snack on raw vegetables like greens, celery, peppers, cucumbers, etc.
- What should I do if I experience headaches & fatigue?
- As your body transitions into the fasting state, it is common to develop headaches and fatigue. This is normal as your body begins to use ketones as fuel. The best way to manage this is to do activities that expend little energy when starting IMF.
- Also, make sure to drink plenty of fluids and eat adequate amounts of sodium. You can try to diffuse some peppermint oil to help relieve headaches.
- How can I deal with the social stigma of not eating?
- Social environments often center around eating. This presents a problem when fasting, as you aren’t consuming food or alcohol. Try aligning your normal eating days with the social events you have that week. Also, tell the people you are with about the fast so you feel sense their support. Additionally, you can order something light like a salad of fresh greens or broth based soup.
SAMPLE PLANS FOR IMF
- Time Restricted Fast:
Ex: 16-hour fast with an 8-hour window of eating to consume normal amount of calories (i.e. 9am-5pm). This is simply eliminating your evening snacking and having an early dinner. Potential perks include better sleep, an empty stomach in the morning, and a hunger for breakfast!
- Modified Fast:
For an 1800 calorie diet-
Monday: Normal calorie intake (1800 calories)
Tuesday: Fast day (20-25% of needs or about 450 calories)
Breakfast: 1 scrambled egg, 1 cup sautéed kale, 1 cup herbal tea, 1 cup water
Lunch: 1 medium carrot and 2 celery stalks cooked in 1 cup bone broth, ¼ cup cooked quinoa, 1/3 cup fresh blueberries
Dinner: 1 cup bone broth, 1 cup sautéed garlic and zucchini, 10 grapes
* Drink all day long! Fill up with lots of hot beverages like herbal teas.
Wednesday: Normal calorie intake (1800 calories)
Thursday: Fast day (20-25% of needs or about 450 calories)
Friday: Normal calorie intake (1800 calories)
Saturday: Normal calorie intake (1800 calories)
Sunday: Normal calorie intake (1800 calories)
READY FOR INTERMITTENT FASTING?
Currently, the science backing IMF in humans is limited.
More human studies are needed to determine the true benefits and possible harm of IMF. However, if you are in good health and like the idea of playing with your diet, then IMF may be right for you!
IMF is a flexible eating approach that can be fit your needs and lifestyle. Follow the step-by-step guide to see how IMF can fit into your life.
Written for Nutrition By Erin