You should avoid carbohydrates for breakfast: The science behind morning metabolism

Breakfast has long been regarded as the cornerstone of a balanced diet, yet the specific composition of this meal remains under scientific scrutiny. Emerging biochemical and nutritional research is shifting focus from whether to eat breakfast towards what to eat at breakfast.

Recent discourse, spurred by biochemist Jessie Inchauspé’s viral explanation of how carbohydrate-heavy breakfasts trigger short-lived dopamine surges and mitochondrial strain, reflects growing interest in how morning nutrition affects energy metabolism and long-term health. Understanding how carbohydrates, proteins, and fats interact with the body’s glucose and insulin systems during the first meal of the day may help redefine metabolic balance and guide dietary choices for improved energy regulation and cardiometabolic health.

How your body responds to glucose intake early in the day

Carbohydrates are the body’s primary energy source, yet the rate at which they are metabolised depends greatly on their type and timing. When simple or refined carbohydrates are consumed early in the day, such as toast, jam, oats with honey, or fruit juice, they are rapidly broken down into glucose, leading to a sharp spike in blood sugar. The body responds with a surge of insulin to lower circulating glucose, which is often followed by a rebound dip below baseline levels.

This sequence, commonly termed the “glucose rollercoaster,” may cause fatigue, hunger, and impaired concentration within hours.Inchauspé’s observation that such breakfasts produce a transient dopamine increase but little sustainable energy finds support in studies examining postprandial glucose dynamics. A 2022 article in Nutrients reported that high-glycaemic meals in the morning were associated with reduced cognitive alertness and shorter attention spans compared with balanced or low-glycaemic alternatives.

While the dopamine rush offers a fleeting sense of wakefulness, it coincides with mitochondrial overload, as cells struggle to convert excess glucose into usable energy.

Repeated exposure to these cycles may weaken mitochondrial efficiency and contribute to oxidative stress, a mechanism implicated in fatigue and metabolic ageing.

Why it matters what you have for breakfast

The broader implications of morning carbohydrate intake extend beyond short-term energy regulation.

A prospective study published in The Journal of Nutrition, Health and Aging investigated how breakfast energy intake and nutritional quality influenced cardiometabolic health in 383 Spanish adults aged 55–75 with metabolic syndrome. Over three years, participants consuming either low-energy or high-energy breakfasts, as well as those with poor breakfast quality (high in refined sugars and low in protein and fibre), exhibited greater body mass index, increased waist circumference, higher triglyceride levels, and lower concentrations of high-density lipoprotein cholesterol.These results illustrate that both the quantity and quality of breakfast calories affect long-term metabolic trajectories. Participants who derived 20 to 30 per cent of their daily energy intake from a nutrient-balanced breakfast, typically containing complex carbohydrates, proteins, and unsaturated fats, maintained healthier lipid profiles and weight stability. In contrast, low-quality breakfasts, dominated by processed grains or sweetened foods, correlated with mild reductions in kidney function and sustained elevations in triglycerides.

The findings highlight that while skipping breakfast can disrupt metabolism, choosing an unbalanced, carbohydrate-dense one may be equally detrimental.

Protein-rich alternatives for breakfast to start your day right

Protein intake at breakfast appears to stabilise glucose levels and enhance satiety by moderating the rate of carbohydrate absorption and stimulating gut-derived hormones such as glucagon-like peptide-1 (GLP-1). This hormonal response prolongs fullness and curbs mid-morning hunger, reducing overall calorie intake across the day.

Studies published in The American Journal of Clinical Nutrition and Metabolism have demonstrated that high-protein breakfasts improve postprandial insulin sensitivity and promote thermogenesis, the process through which the body burns energy during digestion.Mitochondria, responsible for generating cellular energy through oxidative phosphorylation, function more efficiently when nutrient delivery is gradual and balanced.

Protein-based breakfasts, such as eggs, Greek yoghurt, or legumes paired with vegetables, support mitochondrial biogenesis by supplying amino acids that facilitate the repair and formation of new mitochondria. This balanced nutrient profile avoids the metabolic overload seen with high-sugar meals, thereby reducing oxidative damage.

Evidence also suggests that starting the day with protein-rich foods lowers circulating cortisol, helping to maintain a stable stress response and reducing inflammation markers linked to chronic metabolic conditions.

When should you have your breakfast

Beyond macronutrient composition, the order and timing of food intake influence metabolic outcomes. Research into glucose sequencing has revealed that consuming protein and fibre before carbohydrates can attenuate post-meal glucose spikes, even when total carbohydrate intake remains constant. This approach, sometimes referred to as “nutrient sequencing,” aligns with Inchauspé’s recommendation to prioritise protein in the morning to support mitochondrial efficiency.Chrononutrition studies, which examine the interaction between food intake and circadian rhythms, suggest that insulin sensitivity is naturally higher in the morning. However, the body’s ability to process glucose effectively depends on the form of carbohydrate consumed. Refined carbohydrates provide immediate but short-lived energy, whereas complex carbohydrates from whole grains and legumes offer sustained fuel without inducing steep glucose fluctuations.

Balancing these with protein and healthy fats supports the circadian rhythm of metabolic enzymes, ensuring that energy production remains steady throughout the day.

Why the breakfast norms need reforms

Public dietary habits often favour convenience foods such as cereals, pastries, and fruit juices, many of which are marketed as healthy despite containing high levels of refined carbohydrates. The widespread cultural association of sweetness with “morning energy” may inadvertently reinforce glucose instability and contribute to the rising prevalence of insulin resistance and obesity.

By contrast, populations consuming traditional savoury breakfasts, rich in legumes, fermented dairy, or eggs, display lower incidences of metabolic disorders and improved lipid profiles.The evidence from Inchauspé’s biochemical explanation and longitudinal nutritional research converges on a shared principle: the first meal of the day exerts disproportionate influence on the body’s metabolic rhythm. Replacing refined carbohydrates with protein-dense and fibre-rich foods may prevent glucose volatility, optimise mitochondrial output, and support cardiovascular stability. Encouraging this shift in dietary behaviour could reduce the long-term burden of metabolic syndrome and related chronic diseases, aligning personal eating habits with broader public health goals centred on sustainable energy balance and cellular resilience.Disclaimer: This article is for informational purposes only and should not be considered medical advice. Please consult a healthcare professional before making any changes to your diet, medication, or lifestyle.Also Read | Switching from cold coffee to hot coffee: What you should know as winter approaches