What is the most tiring food? A look at nutrition, energy crashes, and sleepiness

November 10, 2025 •

4 min read

According to a study on fruit flies, eating a large meal significantly increases the likelihood of post-meal sleep, indicating a link between meal size and sleepiness. While no single food can be definitively called what is the most tiring food, specific types of meals and ingredients are far more likely to cause significant fatigue and energy crashes than others. This phenomenon, known as postprandial somnolence, is a complex interaction of digestion, hormones, and macronutrient content.

Quick Summary

Examines how processed and sugary carbohydrates, unhealthy fats, and large, calorie-dense meals can trigger significant fatigue and energy dips after eating. Explores the role of hormones like serotonin and blood sugar fluctuations in causing sleepiness. Offers practical strategies for balancing meals to promote sustained energy.

Key Points

High Glycemic Index Foods: Refined carbs like white bread and sugary snacks cause rapid blood sugar spikes followed by a crash, leading to fatigue.
Unhealthy Fats and Large Meals: Saturated fats and large, calorie-dense meals require significant digestive effort, diverting energy and promoting sleepiness via hormones like CCK.
Tryptophan-Rich Foods: When combined with high carbohydrates, foods containing tryptophan (e.g., turkey, cheese) can increase serotonin and melatonin, contributing to drowsiness.
Processed Foods: Ultra-processed foods are low in nutrients and high in inflammatory ingredients, contributing to fatigue and other health issues.
Balanced Meals for Sustained Energy: Combining complex carbs, lean protein, and healthy fats in smaller portions helps maintain stable blood sugar and prevents energy dips.
Timing and Portion Control: Eating smaller, more frequent meals and being mindful of portion sizes can reduce the digestive burden and prevent post-meal slumps.
Hydration and Movement: Staying hydrated and engaging in light physical activity after eating can aid digestion and boost alertness.

Feeling a sudden slump after a big meal, often called a "food coma," is a common experience, but the cause isn't as simple as one specific food. Instead, it's a combination of different factors related to what and how much you eat. The most significant culprits are usually meals high in refined carbohydrates, unhealthy fats, and overall calories, which can disrupt blood sugar and hormone levels. Understanding these mechanisms is key to managing your energy throughout the day.

The Problem with High Glycemic Index Foods

One of the most direct pathways to post-meal fatigue is through foods that cause rapid spikes and crashes in blood sugar. These are known as high glycemic index (GI) foods.

Refined Carbohydrates: Simple carbohydrates, such as white bread, pastries, and sweetened beverages, are digested quickly, flooding your bloodstream with glucose. Your body releases a surge of insulin to manage this glucose, which leads to a rapid drop in blood sugar a short time later. This drop, or "sugar crash," leaves you feeling drained and tired.
Sugary Foods: Desserts, candies, and other sweet snacks provide a similar effect. While they offer a temporary energy boost, the subsequent dip in blood sugar can be more severe, exacerbating feelings of fatigue.

The Role of Macronutrients in Sleepiness

Beyond just sugar, the overall composition of a meal can significantly influence your energy levels. Meals that are particularly high in fats and certain proteins can also contribute to drowsiness.

Tryptophan and Serotonin

Protein-rich foods, especially those high in the amino acid tryptophan, can influence sleepiness. Tryptophan is a precursor to serotonin, a neurotransmitter that regulates mood and sleep, and melatonin, the hormone that promotes sleep. However, tryptophan doesn't act alone; it needs carbohydrates to cross the blood-brain barrier effectively. Therefore, a meal high in both carbs and tryptophan-rich protein (like a heavy pasta dish with cheese) is a potent combination for inducing sleepiness.

Tryptophan-rich foods include turkey, chicken, eggs, cheese, and seeds.

The Impact of High-Fat Meals

Digesting a high-fat meal requires a lot of energy and takes longer than other meals. Fried and fatty foods can trigger the release of hormones like cholecystokinin (CCK), which has been linked to feelings of sleepiness. A large, calorie-dense meal, particularly with saturated and trans fats, can place a significant burden on your digestive system, diverting blood flow from the brain and contributing to lethargy.

Foods high in unhealthy fats often include deep-fried items, baked goods, and fatty cuts of meat.

The Effects of Processed and Inflammatory Foods

Processed foods are often laden with refined sugars, unhealthy fats, and additives, all of which can contribute to fatigue. These foods lack the essential vitamins, minerals, and fiber found in whole foods, which are necessary for efficient bodily functions and sustained energy.

Processed ingredients can cause inflammation in the body, which has been linked to chronic fatigue over time.
The combination of high sugar and refined carbs in ultra-processed foods, like sugary cereals and frozen pizzas, makes it difficult for the body to regulate energy effectively.

Comparison Table: Tiring vs. Energizing Foods


Feature	Tiring Foods	Energizing Foods
Carbohydrates	Simple/Refined (e.g., white bread, sugary snacks)	Complex/Whole Grains (e.g., brown rice, quinoa, oats)
GI Ranking	High Glycemic Index (Quick spike & crash)	Low Glycemic Index (Stable, slow release)
Fats	Saturated/Trans Fats (e.g., fried food, pastries)	Healthy Unsaturated Fats (e.g., avocado, nuts, olive oil)
Meal Size	Large, high-calorie portions	Smaller, balanced portions throughout the day
Processing	Highly Processed (High in additives, low in nutrients)	Whole or Minimally Processed (Rich in fiber, vitamins)
Hormonal Effect	Triggers serotonin/CCK, blood sugar fluctuation	Promotes stable blood sugar and alertness

Practical Ways to Combat Post-Meal Fatigue

Instead of focusing on a single "most tiring food," a more effective strategy is to build balanced and mindful eating habits. Here are some simple steps to prevent that midday slump:

Balance Your Plate: Incorporate a mix of complex carbs, lean protein, and healthy fats in every meal. This slows digestion and glucose absorption, preventing drastic blood sugar swings.
Control Portion Sizes: Opt for smaller, more frequent meals throughout the day rather than three large, heavy ones.
Prioritize Fiber: High-fiber foods, such as vegetables, legumes, and whole grains, further stabilize blood sugar and help maintain energy.
Stay Hydrated: Dehydration can contribute to fatigue, so make sure you're drinking plenty of water throughout the day.
Light Activity: A short walk or some light stretching after a meal can aid digestion and increase alertness.

Conclusion

Identifying what is the most tiring food is less about a single offender and more about the nutritional composition and size of your meal. The primary culprits behind post-meal fatigue are high glycemic index carbohydrates, unhealthy fats, and excessively large portions, which disrupt blood sugar levels and hormonal balance. By shifting your focus from avoiding a single food to adopting balanced eating habits, you can more effectively manage your energy. Incorporating a mix of complex carbohydrates, lean protein, and healthy fats, along with mindful portion sizes, will provide the sustained energy you need to avoid the dreaded food coma and stay productive throughout the day.

Additional Resource

For more information on the effects of diet on energy and fatigue, explore this helpful guide from Harvard Health: Eating to boost energy.

The Connection to Hormones and Digestion

The tired feeling after a meal is a complex process. When you eat, especially a large meal, your body increases blood flow to the digestive system to help break down the food. This can temporarily decrease blood flow to the brain, leading to a feeling of sluggishness. Additionally, the release of hormones and neuropeptides related to digestion and satiety can have overlapping effects with those that regulate sleep. The relationship is intricate, but the overall message remains: what you eat has a direct impact on how your body allocates energy, and a heavy, unbalanced meal is more likely to leave you feeling drained.

Frequently Asked Questions

Eating a large, calorie-dense meal forces your body to direct more energy and blood flow toward the digestive system, which can cause temporary lethargy. The meal's composition, especially if high in refined carbs and fats, can also trigger hormonal changes that contribute to sleepiness.

Yes, some foods are more likely to cause sleepiness. Meals high in refined carbohydrates, unhealthy fats, and large portions are common culprits. Ingredients like tryptophan (found in turkey, cheese) can also play a role, especially when combined with carbohydrates, which aid its conversion to serotonin.

A 'food coma,' or postprandial somnolence, is the natural feeling of sleepiness after eating, especially a heavy meal. While not inherently harmful, frequent or severe food comas can indicate dietary issues that impact your energy levels and overall health. They are often linked to rapid blood sugar changes and hormonal shifts.

To avoid feeling tired, choose complex carbohydrates like whole grains (oats, brown rice), legumes, and vegetables over simple, refined carbs (white bread, pastries). Complex carbs are digested more slowly, providing a sustained release of energy and preventing blood sugar spikes and crashes.

Processed foods are high in refined sugars, unhealthy fats, and additives, and low in essential nutrients like fiber. This can cause inflammation and lead to blood sugar fluctuations, resulting in frequent energy dips and fatigue.

The idea that turkey alone makes you tired is largely a myth. While turkey contains tryptophan, the effect is only significant in the context of a large, high-carbohydrate meal. The combination of carbs and tryptophan is what contributes most to post-meal drowsiness, not the turkey itself.

For sustained energy, eat smaller, balanced meals and snacks every few hours. Incorporate a mix of complex carbohydrates, lean protein, and healthy fats, and prioritize hydration and mindful portion control.