Fasting for Weight Loss: Is it Effective?

Jamie Staley, CPT, Pn1

Photo by Helena Lopes on

What’s the deal with intermittent fasting?

It seems so many people are jumping on the bandwagon of using fasting to reach all kinds of goals and many people credit intermittent fasting with helping them lose weight.

But does it work?

Let’s dive in and see if intermittent fasting would be a good weight-loss strategy for you.

What is Intermittent Fasting?

Intermittent fasting is a diet regimen that cycles between brief periods of fasting, with either no food or significant calorie reduction, and periods of unrestricted eating. 

“Diet Review: Intermittent Fasting for Weight Loss.” The Nutrition Source, 22 May 2019,

A common intermittent fasting protocol is the 16/8 rule, which means you fast for 16 hours per day and can only eat during an 8-hour window each day. Some people take a smaller eating window, but 16/8 seems to be fairly common.

How do I Lose Weight?

So now that we know what intermittent fasting entails, let’s talk about what it takes to lose weight and see if they jive.

Weight loss is only achieved through a negative energy balance. Period. End of story. How you get into a negative energy balance is up to you and there are many ways this can be done: increased activity, decreased caloric intake, or a combination of both.

So does intermittent fasting guarantee a negative energy balance?


Could it create one?


Other Considerations

Aside from intermittent fasting not guaranteeing the outcome you desire, there are other things to consider.

Using intermittent fasting with other methods: some individuals try combining different weight-loss approaches together and end up doing too much. Example: counting calories, eliminating food groups, detoxes or cleanses, and/or an increase in physical activity.

While counting calories while also using a fasting protocol would be necessary to ensure a caloric deficit, it can lead to feeling very deprived. When you are in a calorie deficit, feelings of hunger are very common. The degree to which you feel hungry should not be severe, but it will be present nonetheless.

To be consistent with a calorie deficit for any length of time, it needs to be as minimal and enjoyable as possible. In addition, you want to take steps to minimize hunger during a deficit (spacing out meals, making sure protein and fiber intake is sufficient, eating only when hungry, etc.).

Let’s take increasing physical activity and intermittent fasting as another example. If you are fasting from 8:00 PM to 12:00PM, but add in workouts each morning at 7:00AM, how do you think you will feel by 10:00AM? Hungry and tired! Not to mention the quality of your workouts may very well suffer as a result of not eating beforehand. (This of course varies with each individual, but most of the time when I train a client that has skipped breakfast, it doesn’t go well.)

Using intermittent fasting with medication/medical issues: meal timing can play a huge role in taking certain medications that need to be taken with food and can have a negative impact with some medical conditions such as pregnancy and diabetes.

Women especially need to be careful of using intermittent fasting because of the impact it can have on hormones.

Using intermittent fasting with an eating disorder history: if you have struggled with any type of disordered eating in the past, I would strongly urge you to stay away from intermittent fasting. Restricting your eating window can cause strong restrict/binge cycles that can quickly spiral out of control.

Even if you don’t have a history of disordered eating, intermittent fasting may create a larger issue with your relationship with food.

The Bottom Line

If you are trying to lose weight, try gradual habit change first before jumping to something as drastic as intermittent fasting.


  • drinking enough water
  • 20-30 minutes of activity every day
  • eating 20-30g of protein with each meal
  • eating three servings of vegetables per day
  • cooking most of your meals at home
  • using the hand-portion method
  • limiting highly-processed food
  • planning your meals ahead of time
  • keeping a food log of everything you eat

Once these are under control, you can then adapt more drastic strategies if you are not reaching your goals or your body has adapted to these changes.

Now before I leave here without giving you one pro, setting a time of the day to stop eating can be very helpful to curb boredom eating at night. If you can typically eat dinner by 7:00PM, setting a time of 8:00PM to be done eating for the day is a good idea if all you do is eat garbage after dinner. However, you can keep your breakfast time the same and carry on with the rest of your day as usual.

How Can I Help?

If tackling your nutrition on your own feels too intimidating and confusing, I can help! I am a Level 1 Certified Nutrition Coach through Precision Nutrition, one of the most reputable nutrition companies in the world.

I will coach you through individualized action steps to meet your goals and help you formulate a plan for change that fits your life, instead of trying to make your life fit a plan. I’ll give you the accountability, real information, and guidance to make lasting nutritional change.

Send me an email at and let’s chat about your goals!

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