Focused Eating - Part 1

Part 1: Sugar, Fasting and Omega-3s

By James Collier; Registered Nutritionist; Huel Co-Founder and Head of Sustainable Nutrition

Think back to the last time – probably not that long ago – when you’d had a long, stressful day: tired, hungry, moody and struggling to concentrate. The mere thought of having to appear full of vigour after a long drive home from work drains that last modicum of energy. Lack of food means a lack of energy; however, when it comes to nutrition, our mood and ability to concentrate aren't only controlled by how much we've eaten. Our mental state is also affected by specific nutrients and the overall quality of our diet. When our blood glucose level is low, not only do we feel physically fatigued, but concentration, willpower and self-control are impaired [1]. This is why when you’re hungry and unproductively trying to focus on finishing that piece of work your boss has been nagging you for all week, the wise thing you should do is eat. Research has shown that when we haven't eaten for a while, a single act of self-control causes blood glucose to drop further making it harder to maintain self-control on another task unless we have food [2]. For us to stay motivated, efficient and focused on multiple things, we need to feed ourselves regularly. This may help to explain why people who try to quit cigarettes find they crave sweet foods.

Over the next two articles, we’ll look at some key areas of nutrition issues that influence our ability to focus. In Part 2, we’ll zone in on the boosting effects of hot drinks: both caffeine and their warming effect. Here in Part 1, we’ll look at sugar, fasting and the effects of essential fats on our ability to concentrate.

The Sugar Slump

Whilst having carbs can be useful to help boost our blood glucose, too much can also impede cognitive abilities. Give a six-year-old a bag of sweets and there’s little hope he’ll be sitting still 10 minutes later ready for you to read him a story. More likely he’ll be running around pretending to be Spider-Man. Sugar doesn’t just cause hyperactive kids: diets habitually high in refined carbs impair cognitive function in grown-ups too [3]. Gobbling sugary snacks also affects our short-term concentration. A 2018 New Zealand study compared the cognitive effects of the dietary sugars glucose, fructose and sucrose to placebo (in the form of the artificial sweetener sucralose) [4]. Subjects were given a drink containing one of the sugars, and the group was also divided into two groups, fasting and non-fasting, in order to observe the effects in fasted states. The subjects were given cognitive tasks – which assessed response time, arithmetic processing and attention – and the results showed a negative effect on cognitive functioning from glucose and sucrose, with fructose having no effect. The effect was notably more pronounced in the fasting group. According to the authors “the ‘sugar coma’ – with regards to glucose – is indeed a real phenomenon, where levels of attention seem to decline after consumption of glucose-containing sugar.” Maybe that bag of Haribo on your desk isn’t such a good idea, after all!

Focused Fasting

As well as the simple carbs we devour, our cognitive function and wellbeing are influenced by how regularly we feed ourselves, the nutrient composition of our meals, our background nutritional state, eating habits, food-related beliefs and the nature of the mental tasks we’re performing [5]. For example, having a good breakfast is associated with improved cognitive performance later in the morning, while the wrong lunch choice can land you with the dreaded post-prandial slump, and a healthy meal later in the day appears to boost our ability to perform tasks involving sustained attention or memory [6].

Things are less clear cut when it comes to the effects of fasting. Experiments that have explored the effects of intermittent fasting – i.e. abstinence from food for 12 (often 16, 18 or more) hours for reasons concerning health, religion, discipline, employment or personal preference – on our ability to concentrate have provided us with varied and nuanced results. For instance, research on sleep-deprived night shift workers has shown that eating too large a meal may reduce the ability to perform, and smaller snacks are preferable [7]. Studies on Ramadan-fasting Muslims have indicated a negative impact on educational performance, mental health and decision-making strategies [8]. Others contradict, showing little adverse effect on levels of cognition [9]. Due to such variability in results, a 2021 meta-analysis on temporary abstinence from eating and its effects on cognitive function failed to draw firm conclusions [10].

Will fasting help you stay glued to your monitor for hours or send you drifting into daydream and procrastination? Simply put, it’s hard to say whether the best strategy to stay focused is to chomp down three square meals a day, graze on frequent snacks or to skip breakfast altogether. Most likely, multiple other factors come into play and, if your overall diet is low in sugar and rich in quality food, maybe it doesn’t matter. Although forced abstinence from food may help boost mindset and resilience, when it comes to the issue of fasting and wellbeing, this may be one of those rare occasions when scientists are forced to admit that subjective feelings trump objective data. Deciding if you feel better from prolonged fasting or sticking to regular meals might well be down to you making up your own mind. There is, however, one group of people where the research into the benefits of fasting on cognitive health is extremely encouraging. Several studies using intermittent fasting as an intervention strategy in elderly subjects have indicated improved outcomes [11], indicating benefits for those suffering from brain-related disorders such as dementia, Parkinson’s and stroke.

The Omega Code

There’s one class of nutrients where the evidence is a lot clearer. Research has shown a strong link between omega-3 fatty acids and cognition. We know that modern Western diets with lower intakes of omega-3s risk dire health consequences. In particular, docosahexaenoic acid (DHA) – an omega-3 fatty acid found in oily fish and algae – seems to play a key role in ensuring our cognitive function is maintained as we age [12]. This semi-essential nutrient seems to protect against age-related cognitive decline (ARCD), Alzheimer’s disease and other brain disorders [13], whilst serving to enhance memory, reaction time and strengthening neuroprotection in general [14]. Does this mean that DHA might be our silver bullet in our fight against dementia? Whilst it’s unlikely that DHA is the brain’s panacea opponent of ARCD, there’s reasonable evidence that supplementation with DHA goes some way towards improving learning and memory as we grow older [15]. DHA’s fish oil partner-in-crime eicosapentaenoic acid (EPA) has also been linked to cognitive function; it may help to support attention deficit hyperactivity disorder (ADHD) in children. One encouraging study showed that kids who consumed diets low in omega-3s benefited from fish oil supplements to a level that was at least as effective as conventional pharmacological treatments [16]. Non-fish eaters needn’t despair, however: algae-derived omega-3 supplements are available and diets rich in plant sources of the essential omega-3 alpha-linolenic acid (ALA) allow for sufficient conversion to DHA and EPA.

References:

1. Gailliot MT & Baumeister RF. “The Physiology of Willpower: Linking Blood Glucose to Self-Control.” Personality & Social Psychol Rev. 2007; 11(4):303-27.

2. Gailliot MT, et al. “Self-control relies on glucose as a limited energy source: Willpower is more than a metaphor.” J Personality & Social Psychol. 2007; 92(2):325-36.

3. (a) Ye X, et al. “Habitual sugar intake and cognitive function among middle-aged and older Puerto Ricans without diabetes.” BJN. 2011; 106(9):1423-32. (b) Barnes JN & Joyner MJ. “Sugar highs and lows: the impact of diet on cognitive function.” J Physiol. 2012; 590(12):2831. (c) Chong CP, et al. “Habitual sugar intake and cognitive impairment among multi-ethnic Malaysian older adults.” Clin Interv Aging. 2019; 14:1331-42.

4. Ginieis R, et al. “The ‘sweet’ effect: Comparative assessments of dietary sugars on cognitive performance.” Physiol & Behav. 2018; 184:242-7.

5. Hewlett P, et al. “Grazing, cognitive performance and mood.” Appetite. 2009; 52(1):245-8.

6. Kanarek R. “Psychological effects of snacks and altered meal frequency.” BJN. 1997; 77(S1):S105-S120.

7. Gupta CC, et al. (2019) “Altering meal timing to improve cognitive performance during simulated nightshifts.” Chronobiol Int. 2019; 36(12): 1691-1713.

8. (a) Oosterbeek H & van der Klaauw B. “Ramadan, fasting and educational outcomes.” Econ Ed Rev. 2013; 34:219-26. (b) Masismadi NA, et al. “Ramadan Fasting and the Propensity for Learning: Is There a Cause for Concern?” The Clearing House. 2017; 90(3): 77-85. (c) Cherif A, et al. “Effects of Intermittent Fasting, Caloric Restriction, and Ramadan Intermittent Fasting on Cognitive Performance at Rest and During Exercise in Adults.” Sports Med. 2016; 46:35-47.

9. Mohd Yasin W, et al. “Does religious fasting affect cognitive performance?” Nutr & Food Sci. 2013; 43(5):483-9.

10. Benau EM, et al. “How Does Fasting Affect Cognition? An Updated Systematic Review (2013–2020).” Curr Nutr Rep. 2021; 10:376–90.

11. Examples: (a) Ooi TC, et al. “Intermittent Fasting Enhanced the Cognitive Function in Older Adults with Mild Cognitive Impairment by Inducing Biochemical and Metabolic changes: A 3-Year Progressive Study.” Nutrients. 2020; 12(9):2644. (b) Currenti W, et al. “Association between Time Restricted Feeding and Cognitive Status in Older Italian Adults.” Nutrients. 2021; 13(1):191. (c) Dias G.P, et al. “Intermittent fasting enhances long-term memory consolidation, adult hippocampal neurogenesis, and expression of longevity gene Klotho.” Mol Psychi. 2021; 26:6365-79.

12. Horrocks LA & Yeo YK. “Health benefits of docosahexaenoic acid (DHA).” Pharmacol Res. 1999; 40(3):211-25.

13. (a) Weiser MJ, et al. “Docosahexaenoic Acid and Cognition throughout the Lifespan.” Nutrients. 2016; 8(2):99. (b) Cardoso C, et al. “Dietary DHA and health: Cognitive function ageing.” Nut Res Rev. 2016; 29(2):281-94.

14. Stonehouse W, et al. “DHA supplementation improved both memory and reaction time in healthy young adults: a randomized controlled trial.” Am J Clin Nutr. 2013; 97(5):1134-43.

15. Yurko-Mauro K, et al. “Beneficial effects of docosahexaenoic acid on cognition in age-related cognitive decline.” Alzheimers Dement. 2010; 6(6):456-64.

16. Chang J, et al. “High-dose eicosapentaenoic acid (EPA) improves attention and vigilance in children and adolescents with attention deficit hyperactivity disorder (ADHD) and low endogenous EPA levels.” Transl Psychi. 2019; 9:303 (2019).