Intermittent Fasting (IF) dietary plans have increased in popularity over the past decade, although examples throughout history describe a remarkable variety of fasting forms and practices across different cultures and religions. (1) Involving caloric restriction, which can potentially aid weight control, healthy ageing and longevity, (2) the science is currently observing the success rates for weight loss in obese individuals.
As with any new dietary approach to weight loss, there is never a one size fits all solution. Whether fasting is a safe option for an individual is an important consideration. This week we take a look at what the science says about the potential benefits of IF and evidence of success for weight loss as well as the Do’s and Don’ts and cautions when it comes to using this diet technique.
How Intermittent Fasting works
Intermittent fasting involves going extended time periods with little to no energy intake from food on a recurring basis. (3) The 5:2 diet works by limiting food intake (down to 500-800 calories daily) for 2 consecutive days to reduce overall calorie intake over the space of a week. Another version involves time-restricted feeding daily (usually 16 hours fasting) with only an 8-hour window for consuming food, theoretically reducing daily calorie intake.
What the Science Says.
- The capacity for fasting is an adaptation since humans evolved in environments where food was relatively scarce. Our early ancestors could still function at a high level, both physically and cognitively, when in a food-deprived/fasted state. (3) Over-nutrition – or caloric excess – has moved us further away from the capability to fast, particularly in the Western World. To practice a form of fasting is to therefore return to our more primitive roots, and in general, most Intermittent Fasting regimens are effective and safe (4) with studies typically finding that hunger levels remain stable or decrease during Intermittent Fasting. (5)
Although the focus on fasting via observational studies is limited, the evidence available points more to its success and benefits than any detrimental effects. The few concerns involve safety for individuals (more on this below) and longer-term research is needed to understand the sustainable role Intermittent Fasting can play in weight loss (6) and whether long-term adherence to these regimens (4) can also be sustained.
Benefits and Success
Calorie restriction is proven to be effective in increasing life span, and evidently, nutritional habits and meal frequency can affect sleeping patterns, all of which combined have profound effects on human health. (6)
Intermittent Fasting has shown demonstrated efficacy for improvements in multiple health indicators, including:(1)(3)(5)
- obesity and weight loss
- insulin resistance and Type 2 Diabetes
- cardiovascular disease
- circadian rhythm/sleep
- gut microbiome
The practical length of a daily fasting intervention to effect changes in weight appears to be 16 hours. A 2013 study of 64 obese patients also found that combining exercise with IF doubled weight loss. (5) This study and others have concluded that Intermittent Fasting shows promise for treating obesity.
The Do’s and Don’ts of Intermittent Fasting
- Seek professional guidance before starting a fasting practice
- Get medical clearance and blood sugars checked
- Transition slowly to make the changes sustainable and manageable
- Treat this eating plan as a lifestyle choice
- Eat poorly during the eating window
- Expect a quick fix for weight loss
Why IF may not be right for you
If you have a history of Eating Disorder – Importantly, restricting calories requires a healthy mindset and may not suit everyone to help achieve a weight loss goal. For example, a person who may have experienced an Eating Disorder may want to avoid a cycle of food deprivation, leading to excessive food intake or bingeing.
If you have a tendency for hypoglycaemia – Use of Intermittent Fasting in patients with diabetes poses a risk of hypoglycemia (5) in patients who are treated with medication including insulin or sulphonylureas. (4) There is still the potential for a modified version of this eating plan under the guidance of a practitioner and with regular blood glucose monitoring, but caution is advised.
The future of fasting
Interestingly, some experts recommend that future studies consider strategies for tailoring fasting prescriptions based on advanced phenotyping and genotyping and (2) using genetics to determine if fasting suits the individual. Until such time, our Naturopaths and Nutritionists can expertly guide you through the process of dietary change or help you decide if you are unsure whether a fasting approach is right for you. Keep in mind that when it comes to Intermittent Fasting, the desired results may not be seen until a little while into the future!