trending diets: intermittent fasting

August 20, 2019

It’s hard to know which of the currently trending diet options will work for you and your lifestyle, which is why we started this blog series with our Registered Dietitian Nutritionist, Amy Haynes. We’re back at it again this month with an in-depth look into intermittent fasting and its benefits and potential hidden pitfalls. Remember that while these tips came from a professional nutritionist, it’s important to always check in with your doctor before starting a new diet.

If you’re already an intermittent fasting pro, skip to the end to find some new tips for how to get through your next fast.


Fasting as a general concept started out of evolutionary necessity. Before things like farming, grocery stores and UberEATS, it could be quite difficult for people to find or hunt down food and they often had to go many hours or days without eating. Humans developed the ability to go extended periods of time without food as a survival technique. Like many diets, intermittent fasting is typically adopted to induce weight loss, however, is can also be used as a detoxifying regimen. There are many different types of intermittent fast scenarios, all of which involve abstaining from food for an extended period. These scenarios can range from specific daily eating patterns to full 24-72-hour weekly fasts. Some of the most popular regimens people choose people choose to follow include:

  • 16/8 – Consume meals during an 8-hour window and fast for 16 hours
  • 12/12 – Consume meals during a 12-hour window and fast for 12 hours
  • 20 Hour – Consume meals during a 4-hour window and fast for 20 hours
  • 5:2 – Choose 2 non-consecutive days of the week and limit intake on those days to 500 calories or less for women and 600 calories or less for men.
  • Alternate Day Fasting – Fast every other day, and on fasting days reduce caloric consumption to 25% of normal intake. 400-500 calories per day for women and 500-600 calories for men is the guideline recommended for the average person.
  • 72 Hour – Abstain from food for 3 days straight


Intermittent fasting hasn’t gained popularity for no reason, it can have several benefits to your overall health and weight. Studies evaluating alternate day fasting have shown cardiovascular benefits, including decreased triglyceride levels (this can help your risk of a stroke), improvement in the health of circulating cholesterol particles as well as lower fasting blood glucose and promote favorable insulin concentration. This means that those following a regular intermittent fasting schedule can have reduced diabetes incidents.

Many who are using intermittent fast for weight loss find that it’s easier overall to fast and only feel hungry on fasting days versus following a low-calorie diet daily and feeling hungry all the time. On non-fasting days, they can consume foods as normal and look forward to not feeling hungry. This type of diet isn’t as regimented or demanding when compared to other trending diets such as ketogenic or paleo because it doesn’t require time consuming meal preparation or any restricted food groups.

There is some fear that intermittent fasting might lead to overconsuming calories on non-fasting days, but this fear has been found to be unwarranted in most cases. Although calorie consumption on non-fasting days tends to be about 10 percent greater than normal, it still leaves the faster with a calorie deficit over time, which ultimately leads to weight loss.

Critics of intermittent fasting have theorized that it could have an adverse effect on the faster’s resting metabolic rate and lean body mass. This is due to many calorie restricted diets leading to loss of muscle mass, which directly translates to a decreased resting metabolic rate. This has been proven to be untrue to intermittent fasters. Studies of subjects following intermittent fasting for weight loss show 90 percent fast loss and only 10 percent muscle loss, which has no effect on resting metabolic rate.


While there are plenty of benefits to intermittent fasting, it definitely isn’t for everyone. Fasters can experience severe hunger pangs, fatigue, headaches, muscle cramps and decreased concentration during fasting periods. Or in other words, you can get pretty hangry when you haven’t eaten in 12 hours.

It can be very hard to adhere to an intermittent fasting plan when you’re used to eating every 2-3 hours and depending on the regimen, staying committed can be difficult in everyday life. Much of our social lives as Americans revolves around going out and getting food together, it can be awkward to not participate in those social norms.


The biggest risk when practicing intermittent fast is the possibility of under-consuming essential nutrients. If your non-fasting periods/days don’t include a variety of nutrient dense foods, you will start to feel the ill-effects of becoming nutrient deficient. You should always consult your doctor about the nutrients your body will need to consume during non-fasting periods.

At this point, there isn’t a lot of research that has been conducted on the long-term effects of intermittent fast for weight loss in humans. While that isn’t necessary an immediate risk, it’s good to be aware that even nutrition professionals don’t quite know what the long-term effects on your body will be.

In general, intermittent fasting is not recommended for the following people:

  • Women who are pregnant or breastfeeding
  • Those with diabetes, especially those who are insulin dependent
  • Anyone with health conditions requiring medication
  • Anyone with a history of disordered eating

Best Practices

If you’re interested in trying out intermittent fasting for yourself, Amy has a few best practices and tips to help you get started and make it through your first fast.

  • In general, it is important to stay hydrated during your fasting period. Try preparing a pitcher of infused water to drink to keep your body more satiated. Below are a few flavor ideas:
    • Lemon-Cucumber
    • Strawberry-Basil
    • Orange-Kiwi
    • Raspberry-Mint
  • Avoid drinking diet sodas or adding any artificial sweeteners to beverages because this will spike your insulin levels and take you out of fasting mode.
  • Adding a splash of apple cider vinegar to still or sparkling water can help you regulate your blood sugar and add a bit of flavor.
    • Pro Tip: Start with 2 Tbsp. of apple cider vinegar per 8 fluid oz of water. If it’s too strong, add more water to taste.
  • Another option to add flavor to your water is dropping in a pinch of pink Himalayan salt. This can also help combat headaches due to salt withdrawal.
  • Sipping on bone broth or vegetable broth is acceptable during fasting periods.
  • During non-fasting periods, be sure to consume adequate fiber, which can be found in vegetables, fruits, whole grains, nuts and seeds.


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