What is intermittent fasting?
Intermittent fasting (IF) is a pattern of eating that alternates between periods of fasting and eating. The fasts can be:
- Daily (e.g fasting for 16hours and allowing an 8-hour eating window)
- Weekly (e.g. fasting for 24hours 1-2 days per week)
- Yearly (e.g. fasting for 3-5 days once or twice a year).
These diets have a strong media presence and have been linked with many celebrities. They seem to be popular because of their simple nature.
There are typically two goals for people who fast. Either weight loss, or optimisation of health markers, with or without weight loss.
Can Intermittent fasting help with either of these goals?
Weight loss can occur simply as a result of a shorter feeding window leading to reduced calorie intake. The research that we have to date, has shown no significant differences in weight loss, blood fat concentrations, blood sugar levels and insulin levels in those who engage in continuous restriction (the type that characterises other diets), compared to IF (1, 2). *
The longer-term effects (beyond 12 months) of this approach remain unclear, and further research is therefore required.
What are some of the benefits of avoiding eating before bedtime?
Late-night eating is typically defined as eating past 8 pm. There is some research that may support the benefits of eating the biggest calorie meal earlier in the day on blood fats and blood sugar levels, but much of the research we have around nighttime eating is conducted in shift workers who have quite extreme patterns.
It’s important to highlight the huge amount of class privilege that comes with being able to choose the timing of eating. Some people can’t even eat consistently, because they can’t afford it.
Humans are complex, and putting time restrictions on eating is often not practical and does not allow the individual to honour their natural hunger signals. As a clinician, I encourage individuals to pursue what feels and works best for them.
So if not intermittent fasting, what would you recommend to control weight?
There is limited evidence to support the long-term benefits of weight loss. Whilst we know that weight loss is possible in the short term, there is overwhelming evidence that shows any form of intentional weight loss has no long-term success.
Regardless of the degree of initial weight loss seen with lifestyle intervention, most weight is regained within a 2 year period, and by 5 years the majority of people are at their pre-intervention weight.
We’re often led to believe that dieting in any form is pretty safe and harmless. However, what we’ve now come to know through research, and clinical experience, is that dieting can lead to all sorts of complex mental and physical issues. Common issues include things like binge eating, feeling addicted to certain foods, anxiety, stress and shame around food, eating disorders and disordered eating, weight yo-yoing, or weight increasing with each and every diet attempt.
For this reason, I take a Non-Diet approach and weight inclusive approach to nutrition (Intuitive Eating) which is an evidenced-based practice that supports the pursuit of health without focusing on weight or body size. This approach supports health-promoting lifestyle which have been proven to improve health regardless of changes in body weight.
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