Science of Breakfast

When looking at a new client’s food diary, one of the things that most nutrition advisers will almost certainly pick out, is the absence of breakfast.

School Of Nutrition Posted May 23, 2017 Future Fit Training

Science of Breakfast

Breakfast is always talked about as the ‘most important meal’ of the day, and linked with healthy eating and weight loss but what does the science say?

Breakfast and BMI

Population studies in many different countries have shown that people who eat breakfast do on average have lower BMIs and this relationship is particularly strong in children and adolescents (1-6). Although this looks conclusive, despite many large and well designed intervention trials, there is to date no evidence, that not eating breakfast causes weight gain or prevents weight loss (7). It maybe that eating breakfast is a marker of a generally better diet or a more active life style, rather than having a direct causal effect on weight and more studies are needed.

Eating more during the day

It would make sense that skipping breakfast (or any meal) would cause you to be hungrier and so to eat more at later meals, possibly causing over-eating. However, contrary to this, most studies have shown that skipping breakfast actually results in a lower total energy intake over the course of a day. Although individuals do eat more at other meals, they never make up for the calories they missed out on. So, despite greater hunger (8) and eating more at other meals (9), there is no evidence that skipping breakfast causes people to eat more or put on weight (10).

Craving sweet things and the 4pm munchies

Missing meals and having large gaps between eating has been conclusively shown to enhance the appeal of highly palatable, high calorie foods (11) and there is the suggestion that outside a scientific trial setting, when the individuals do not feel they are being watched, that this may result in higher calorie intakes. There is also indisputable evidence that the high-risk time for non-breakfast eaters is not mid-morning or lunch time as would be expected but is after 4pm (8-10).

Positives for breakfast

Eating breakfast not only provides the body with macro and micro nutrients, the action of eating also sets a variety of biological processes in motion. We are only just starting to fully understand how this works but we do know that eating breakfast increases energy expenditure through diet induced thermogenesis (DIT) (12) and causes individuals to be generally more active during the morning (13). Although energy intake overall is similar in breakfast and no breakfast eaters, trials have shown 4.5% improved exercise performance in individuals who eat breakfast (14). Eating breakfast is also know to be important in re-setting your circadian clock and in regulating sleep and poor sleep is associated with both greater hunger and weight gain.

Long term effects

Skipping breakfast has a significant effect on insulin sensitivity and both blood sugar and blood lipid profiles, increasing LDL cholesterol and insulin resistance risk and slowing metabolism (15) – all of which will increase the chance of weight gain and health risks over time. Eating breakfast is particularly important for people who already have diabetes or pre-diabetes as fasting till noon can increase after meal blood sugar and impair the insulin response at both lunch and dinner (16).

So, despite there being little evidence that eating breakfast helps weight loss or stops weight gain, long term it could be incredibly important, improving the balance of what you eat, lowering the desire to eat sweet things, stopping the 4pm munchies and lowering health risks. One study has found that people who skip breakfast as children are 68% more likely to have metabolic syndrome and diabetes in middle age (17) and it's never too late to improve your health.

If you would like to know more about how the foods we eat on a daily basis affect our bodies, then our Nutrition and Weight Management course is perfect for you.


1. CHO et al (2003). The effect of breakfast type on total daily energy intake and Body Mass Index: results from the third national health and nutrition examination survey (NHANES III). J Am Coll Nutr 22(4):296-302

2. Kant et al (2008). Association of breakfast energy density with diet quality and body mass index in American adults: National health and Nutrition surveys 1999-2004. Am J Clin Nutr 88(5):1396-404.

3. Berkey CS, Rockett HR, Gillman MW, et al. Longitudinal study of skipping breakfast and weight change in adolescents. Int J Obes Relat Metab Disord. 2003;27:1258–1266. 

4. Keski-Rahkonen A, Kaprio J, Rissanen A, et al. Breakfast skipping and health-compromising behaviors in adolescents and adults. Eur J Clin Nutr. 2003;57:842–853.  

5. Rampersaud GC, Pereira MA, Girard BL, et al. Breakfast habits, nutritional status, body weight, and academic performance in children and adolescents. J Am Diet Assoc. 2005;105:743–760. (quiz 761–762)

6. Utter J, Scragg R, Mhurchu CN, et al. At-home breakfast consumption among New Zealand children: associations with body mass index and related nutrition behaviors. J Am Diet Assoc. 2007;107:570–576

7. Dhurandhar et al (2014). The effectiveness of breakfast recommendations on weight loss:a randomised controlled trial. Am J Clin Nutr 100(2):507-13

8. Chowdhury et al (2015). Effect of extended morning fasting upon ad libitum lunch intake and associated metabolic and hormonal responses in obese adults. Int J Obesity 40:305-311.

9. Chowdhury et al (2015). Carbohydrate-rich breakfast attenuated glycemic insulinaemic and ghrelin response to ad libitum lunch relative to morning fasting in lean adults. Brit J Nutrition 114(1):98-107.

10. Reeves et al (2014). Experimental manipulation of breakfast in normal and overweight/obese participants is associated with changes to nutrition and energy intake consumption patterns. Physiol Behav 22(133):130-135.

11. Goldstone et al (2009). Fasting biases reward systems towards high calorie foods. Eur J Neurosci 30(8):1625-35.

12. Bo et al (2015). Is the timing of caloric intake associated with variation in diet-induced thermogenesis and in the metabolic pattern? A randomised cross over study. Inter J of Obesity 39:1689-1695

13. Chowdhury et al (2016).  The causal role of breakfast in energy balance and health: a randomised control trial in obese adults. Am J Clin Nutr DOI:10.3945/ajcn.115.122044

14. Clayton et al (2015). Effect of breakfast omission on energy intake and evening exercise performance. Med Sci Sports Exercise 47(12): 2645-52.

15. Farshchi et al (2005). Deleterious effects of omitting breakfast on insulin sensitivity and fasting lipid profiles in healthy lean women. Am J Clin Nutr 81(2):388-396

16. Farschi et al (2005). Beneficial metabolic effects of regular meal frequency on dietary thermogenesis, insulin sensitivity and fasting lipid profiles in healthy obese women. Am J Clin Nutr 81(1):16-24

17. Wennberg et al (2015). Poor breakfast habits in adolescence predict the metabolic syndrome in adulthood. Public Health Nutrition 18(1):122-129.

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