Intermittent Fasting (IF) is perhaps one of the most asked about nutrition topics by our Members. It has gained attention in both mainstream media and in the world of academic research as a tool for weight loss, managing blood sugar, and increasing longevity. At the same, misleading information is also surfacing, especially on social media, which clouds the science and research-based evidence currently published on this topic. SHIFT Dietitians seek to separate fact from fiction on this topic and to provide reliable information to Members considering intermittent fasting as a method of weight loss.
Intermittent fasting is a dietary regime that alternates periods of fasting (or drastically restricted calorie intake) with periods of unrestricted intake. While there are a variety of different types of IF, including alternate-day fasting, the most common type is called “time-restricted feeding.” This involves non-restricted intake within specified time frames followed by extended fasting intervals (typically anywhere from 12-18 hours).
Current Research on IF
A newer, in-depth review published in New England Journal of Medicine in December 2019, suggests there is good evidence that a circadian rhythm fasting approach (meals are restricted to an 8-10 hour period of daytime), when combined with calorie restriction and a healthy diet and lifestyle (i.e. balanced meals, regular exercise, stress management, adequate sleep, etc.), can be a particularly effective approach to weight loss.
While more long-term and comprehensive studies need to be performed, the current state of the literature concludes:
- Intermittent Fasting can lead to improvements in health metrics, like weight loss, body composition measures, blood pressure, blood sugar control and cholesterol if the fasting regimen creates a calorie deficit.
- Limited data show improved clinical outcomes for other medical conditions, such as diabetes, heart disease, and Alzheimer’s.
- Research on increased lifespan and cell longevity as a result of IF is inconclusive in humans.
- Research has not shown IF to be superior to other calorie deficit diets for weight loss.
So, in summary, current studies have shown that intermittent fasting can be an effective approach to weight loss if executed in a sustainable way that produces a calorie deficit and that prioritizes a healthy diet and active lifestyle. Ultimately, the best approach for you will be the nutrition approach that you can maintain for the long-term.
Putting Intermittent Fasting into Practice
While studies thus far suggest IF is not harmful for the general population, this regimen could be inappropriate for certain groups, including people:
- With diabetes
- With eating disorders
- Taking medications that require regular energy intake
- Trying to gain muscle mass
- Who are pregnant or breastfeeding
Reach out to your SHIFT Dietitian before trying Intermittent Fasting to ensure it is appropriate and safe for you.
If deemed appropriate, your SHIFT Dietitian will help you create a fueling window that fits your lifestyle/activity level. In general, remember to keep the SHIFT Nutrition Pillars in mind:
NUTRIENT DENSITY: Focus on getting plenty of fruits and vegetables, fiber-filled foods, healthy fats, high-quality lean proteins, and whole grains.
NUTRIENT BALANCE: Aim for the Balanced Plate at meals and prioritize lean proteins at snack times.
NUTRIENT TIMING: While your eating window will be shortened, it is still important to fuel consistently and ensure you are prefueling/refueling for your workouts.
EATING INTUITION: Most importantly, listen to your body. If you are feeling especially weak, light-headed, or physically hungry during your fasting window, don’t force it. IF is not for everyone and can lead to food disorders or unhealthy relationships with food for some.
No matter what approach you take, keep the SHIFT Nutrition Pillars front and center in your mind. By eating high quality foods and hydrating at the right times and in the proper proportions, we aim to create energizing and beneficial effects in the short term and positive health outcomes in the long term. The Pillars support our health in a fundamental way and help foster a healthy relationship with food.
Tavierney & Lauren