Does intermittent fasting work? (Guest post by Alex Neilan “The Sport Dietitian)

I’m really pleased to be able to bring you some advice from Edinburgh’s top dietitian, Alex “The Sport Dietitian” Neilan. This will be the first of regular input from Alex. The goal is to bring you solid, evidence-based dietry advice to help you stay healthy and maximise your performance.

What is intermittent fasting?

Intermittent fasting is an eating pattern where you cycle between periods of eating and fasting. Intermittent fasting is not a diet, rather a dietary pattern, meaning it does not dictate which food should be eaten, rather when food should be eaten. Intermittent fasting is currently very popular among the health and fitness

There are several different intermittent fasting methods:

 The 16/8 method – fasting for 16 hours per day and eating during the 8-hour
eating window (e.g. skipping breakfast, eating your first meal at 12pm and
your last meal before 8pm)
 The 5:2 diet- eating as normal for 5 days of the week then eating 500-600
calories on 2 days of the week
 Eat-stop-eat – a 24-hour fast once or twice per week (avoiding eating after
dinner one day until dinner the following day)

The most popular method is the 16/8 method. Working individuals who struggle to
find extra time in the morning may find this method convenient. It is also convenient
for those who exercise in the evening and tend not to require as much energy in the

Is Intermittent fasting necessary for weight loss?

As your eating window is restricted, this will naturally result in less food being eaten.
Less food eaten = decreased calorie intake = weight loss.

However, Trepanowski et al (2017) found that intermittent fasting is not superior to daily calorie restriction with regards to adherence, weight loss, weight maintenance, or improvement in risk indicators for cardiovascular disease.

When can it work?

Intermittent fasting can work when you simply cannot stomach food in the morning or if you can’t make time for breakfast. It can also work in comparison to not making
any changes to your current eating habits. Harris et al (2018) found that intermittent fasting may be an effective strategy for the treatment of overweight and obesity, and
was shown to be more effective than no treatment. Furthermore, Patterson & Sears
(2017) found that an intermittent fasting regimen may be a promising approach to losing weight for people who can safely tolerate intervals of not eating, or eating very little, for certain hours of the day, night, or days of the week.

What are the downsides?

Reduces our metabolism
The longer we are in a fasted state, the longer we experience catabolism (breaking down muscle). This is strongly related with reducing our metabolism. Small, frequent protein feedings of 20-30g five times a day has been shown to be superior in maximizing protein synthesis, compared to consuming protein in larger doses, less frequently (Burke et al, 2010). Protein synthesis is a key ingredient to enable us to maintain our muscle mass when adhering to a calorie deficit, in order to achieve weight loss. There is a direct
correlation between muscle mass, metabolically active tissue and metabolism. The more muscle mass we have, the higher our metabolism. Put simply, the more
muscle mass we can retain, the more calories we can eat BEFORE gaining body fat.
And let’s face it… EATING MORE BEFORE GAINING BODY FAT IS THE DREAM. Therefore, when we fast, we reduce the effectiveness of protein synthesis, which negatively affects the amount of muscle mass we can retain during a calorie deficit (eating less calories than we are burning off). This, in turn, can reduce our metabolism and make achieving sustainable weight loss more difficult.

You may suffer from HUNGER (I can’t deal with this)

The longer you fast, the more likely it is that you will feel hungry – rocket science, I know.

You won’t be able to train efficiently in the morning

Training fasted without efficient fuel for energy will be a hungry thorn in your side. There is a world of evidence supporting the importance of carbohydrate pre-exercise
to maximise performance (Burke, 2017).

Bad Breath

Intermittent fasting can lead to reduce salivary flow which is linked with bad breath
(Rosenburg, 2009). Not cool, guys.

Your work performance will suffer

Why do we eat? We eat for enjoyment, health and cultural benefits. We eat to survive; we eat to perform physically and mentally. When fasted, our reaction time, problem solving abilities and ability to keep our cool in during stressful situations is greatly reduced. So, if you want to be at your best at work, make sure you have your brekkie.

The take-home message…

Intermittent fasting is not necessary for weight loss and does have a great deal of downsides. There is an EASIER WAY…. eating a well-balanced diet with the correct macronutrient structure will minimise hunger, maximise food palatability and
eliminates the feeling that you are on a “Diet” (hate that word).
Furthermore, getting a convenient eating structure with regular accountability, motivation and behaviour change support is the key to true SUSTAINABLE RESULTS. And let’s face it – if we are making the effort to adapt our current eating
habits, the results we obtain had better be goddamn SUSTAINABLE.

Book in a consultation above to discuss your personal barriers and how I can help.

If you’d like to feel less self-conscious in how you look, live longer or gain clarity on the optimal evidence based nutritional strategy for your sports performance,  click

>>>HERE ( to book a free strategy call with Alex.


Burke, L, Hawley, J, Wong, S. and Jeukendrup. 2011. Carbohydrates for training and competition,
Journal of Sports Sciences, 29:sup1, pp 17-27.

Burke, L., Gibala, M. and Van Loon, L. 2010. Nutritional Strategies to Promote Post exercise
Recovery. International Journal of Sport Nutrition and Exercise Metabolism. 20, pp 515-532.

Harris, L., Hamilton, S., Azevedo, L. B., Olajide, J., De Brun, C., Waller, G., & Ells, L. 2018.
Intermittent fasting interventions for treatment of overweight and obesity in adults: a systematic review
and meta-analysis. JBI database of systematic reviews and implementation reports, 16(2), 507-547.

Patterson, R. E., & Sears, D. D. 2017 Metabolic effects of intermittent fasting. Annual review of
nutrition, pp 37.

Rosenberg, M.2009. Bad Breath: Research Perspectives. Ramot Publishing, Tel Aviv; second edition,
1; 965-274, pp 173-176.

Trepanowski, J. F., Kroeger, C. M., Barnosky, A., Klempel, M. C., Bhutani, S., Hoddy, K. K., &
Ravussin, E. 2017. Effect of alternate-day fasting on weight loss, weight maintenance, and
cardioprotection among metabolically healthy obese adults: a randomized clinical trial. JAMA internal
medicine, 177(7), pp 930-938.

One Reply to “Does intermittent fasting work? (Guest post by Alex Neilan “The Sport Dietitian)”

  1. Nice and simple way to get the message across, I’ll be sharing this with my wife who seems to be on an endless diet.


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