Does Intermittent Fasting Work?

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This weeks blog is all about intermittent fasting. It’s been a hot topic for a number of years now but rarely see a balanced argument discussed. Therefore, I looked into the proposed benefits for you to help put the science back into nutrition.

What is intermittent fasting? 

There is no true system of intermittent fasting. The principles is based on two systems. Either reducing the amount of calories you eat on some days or only eating during set times of the day.  The research has focused on 3 main types. Alternate day fasting involves eating nothing one day followed by a habitual diet the following day. Modified fasting is the most common and popular. This system involves eating less on certain days like the 5:2 diet. Finally, time restricted fasting refers to only eating during specific hours of the day. However, technically you could go rogue and implement this method in any format you wish.  This is in contrast to typical healthy eating advice. This usually focuses on continuous energy/calorie restriction. 

What’s the proposed benefit? 

The theory behind intermittent fasting is it allows the body to tap into its fat stores allowing you to lose weight. Also, by reducing the amount or time you eat, you will have fewer calories.  Further to this it is claimed intermittent fasting improves hormone sensitivity, can increase satiety,  reduces inflammation in the body, improves cellular repair, improves gut microbiota and reduces lipids in the circulation.  Quite the claims. 

Should I be following an intermittent fasting programme?

Although research into intermittent fasting is promising, it shows no extra benefit of traditional dietary methods. In fact, every article I read showed comparable outcomes between intermittent fasting and continuous calorie restriction.  This is still significant because it is as effective as other diets. Therefore, if such a method works for you and you are able to stick with it, it could be a great option for long term success.  However, evidence for the long term effects is missing at present.  Also, most of the research conducted to date has focused on rodents, religious fasting or has less than 50 participants. In other words, it’s hardly robust evidence. When data is lacking it’s hard to say whether more data will show more or less benefit.  Animal studies in particular often struggle to be applied to humans. Even if the findings apply to humans physiologically it can be difficult to replicate in humans. Tests in animals can be completely controlled. In other words, we feed them what they want and they can’t do a thing a about it.  Humans on the other hand tend to be a bit more picky. Particularly outside of the lab environment.  So even if something works in a study, once we’re back in our normal lives surrounded by temptation and every day stress, things are slightly skewed. 


Like weight loss, no evidence suggests intermittent fasting is a superior method over other methods for managing type 2 diabetes. It seems however intermittent fasting is as an effective method as continuous energy restriction for weight loss. Seeing as weight loss is the cornerstone of most type 2 diabetes management, intermittent fasting could be used as an alternative method to help improve your type 2 diabetes management.  Remember, if you take insulin or use sulphonylureas you may be at risk of a low blood glucose level on your fast days. Therefore, you may need to adjust your medication doses accordingly. Speak with your team before commencing any diet if you such medications. Ultimately, it seems the best diet is one you can stick to. Of course, this is assuming it is safe and doesn’t cut out major nutrients from your diet. This may be true particularly if you are someone who would find it easier to be strict on certain days and slightly more relaxed on others, this could be for you.  Consistency is key on any diet.  So if you do join the intermittent fasting trend I would strongly advise to make sure you’re prepared to stick with it for the long term. 


Ultimately, intermittent fasting achieves the same as other diets on the market. Intermittent fasting might be a useful method for dieting if it works for you. The concern would be not many diets show long term success and this may well fall into that category. Time will tell.  It is comparable to continuous calorie restriction in terms of weight loss and health outcomes. Those that struggle to regularly control their intake and would rather set aside specific times of reduced eating might benefit from this.  If taking medication it is wise to speak with your healthcare team before significantly reducing your calories on certain days to prevent ill effects.  However, as it stands, the claims of intermittent fasting being superior for your health are not founded.

Need more help

If you need more support we offer a range of 1:1 consultancy services and online programmes focused on helping you improve your glucose control and health for the long term. These include our type 2 diabetes recovery programme, type 1 glucose stability programme and winning weight loss programme. Go to the pages using the links above or in the headers or get in touch if you have questions.

Reference List

Could Intermittent Energy Restriction and Intermittent Fasting Reduce Rates of Cancer in Obese, Overweight, and Normal-Weight Subjects? A Summary of Evidence. Dietary Interventions for the Prevention of Type 2 Diabetes in High-Risk Groups: Current State of Evidence and Future Research Needs. Effects of eight weeks of time?restricted feeding (16/8) on basal metabolism, maximal strength, body composition, inflammation, and cardiovascular risk factors in resistance?trained males. Effect of intermittent compared to continuous energy restriction on weight loss and weight maintenance after 12 months in healthy overweight or obese adults. The effects of intermittent compared to continuous energy restriction on glycaemic control in type 2 diabetes; a pragmatic pilot trial. Effect of intermittent versus continuous energy restriction on weight loss, maintenance and cardiometabolic risk: A randomized 1-year trial. Effectiveness of Intermittent Fasting and Time-Restricted Feeding Compared to Continuous Energy Restriction for Weight Loss. Intermittent energy restriction in type 2 diabetes: A short discussion of medication management Intermittent fasting and human metabolic health. Intermittent v. continuous energy restriction: differential effects on postprandial glucose and lipid metabolism following matched weight loss in overweight/obese participants. Intermittent fasting in Type 2 diabetes mellitus and the risk of hypoglycaemia: a randomized controlled trial. Metabolic Effects of Intermittent Fasting. Therapeutic use of intermittent fasting for people with type 2 diabetes as an alternative to insulin.