Should a skinnier person eat more or less when bulking up?

October 9, 2025 •

4 min read

To gain weight and build muscle, a person must consume more calories than their body burns. So, to answer the question, "Should a skinnier person eat more or less when bulking up?", the definitive answer is more. This is especially true for those with a naturally high metabolism, often referred to as ectomorphs.

Quick Summary

This article explains that skinnier individuals need to consume more calories, in a controlled surplus, to build muscle effectively. It discusses the difference between clean and dirty bulking, detailing macronutrient needs, meal timing, and the importance of tracking progress for optimal gains.

Key Points

Controlled Calorie Surplus: Skinnier individuals need to eat more calories than they burn, specifically aiming for a moderate surplus of 300-500 kcal per day, to gain muscle effectively.
Embrace the 'Clean Bulk': A clean bulk, focusing on nutrient-dense, whole foods, minimizes fat gain and supports better long-term health compared to an unregulated 'dirty bulk'.
Optimize Macronutrient Ratios: As ectomorphs, a higher proportion of calories from carbohydrates (50-60%) is beneficial to fuel intense training, alongside adequate protein for muscle repair.
Incorporate Calorie-Dense Foods: Utilize healthy, high-calorie additions like nuts, avocados, and oils, as well as protein-rich shakes, to meet elevated caloric needs without excessive volume.
Track Your Progress: Regularly monitoring body weight and strength gains is crucial to ensure you are gaining muscle and not excessive fat, allowing for timely caloric adjustments.

Caloric Surplus: The Foundation for Bulking

For a skinnier person, or an ectomorph, building muscle mass requires a consistent caloric surplus. This means consuming more calories each day than the body expends through exercise and daily activities. A common mistake is assuming that because you are naturally thin, you can eat anything and still put on lean mass. While it is true that you have a higher metabolic rate, excess calories, even for a skinny person, will be stored as fat if not properly utilized. Therefore, a strategic, controlled approach is essential for a successful bulk.

Calculating Your Calorie Needs

First, determine your Total Daily Energy Expenditure (TDEE), which is the number of calories your body burns in a day. Online calculators can help estimate this based on your age, sex, weight, height, and activity level. Once you have this number, you can create a calorie surplus. For beginners and ectomorphs, a good starting point is adding an extra 300-500 calories per day to your maintenance level. This moderate surplus helps ensure that a greater proportion of the weight gained is muscle rather than fat. Track your weight weekly, and if you are not gaining around 0.25-0.5% of your body weight per week, consider increasing your intake by another 200-250 calories.

Clean vs. Dirty Bulking: The Better Choice

When gaining weight, you have two main options: a clean bulk or a dirty bulk. For long-term health and a lean physique, a clean bulk is the superior choice, especially for those prone to gaining fat during an uncontrolled bulk.

The Role of Macronutrients

While total calories are important, the source of those calories is crucial. Macronutrients—protein, carbohydrates, and fats—play specific roles in muscle growth and recovery. For skinnier individuals (ectomorphs) who have a higher tolerance for carbohydrates, a higher carb intake is recommended to fuel intense workouts and replenish glycogen stores.

Protein: The building block of muscle. Aim for a consistent intake of 1.6–2.2 grams of protein per kilogram of body weight per day to support muscle repair and growth. Lean sources include chicken breast, fish, eggs, and dairy.
Carbohydrates: The body's primary energy source. Ectomorphs often require 50-60% of their total calories from carbs to fuel workouts effectively. Focus on complex carbs like oats, brown rice, quinoa, and sweet potatoes.
Fats: Essential for hormone production and overall health. Healthy fats should make up around 15-25% of your daily calories and can be found in avocados, nuts, seeds, and olive oil.

Practical Strategies for Increased Intake

For many skinnier individuals, eating more can be a challenge due to smaller appetites. The key is to focus on calorie-dense, nutrient-rich foods and increase meal frequency.

Tips for Increasing Calorie Intake Healthily:

Eat more frequently: Instead of three large meals, aim for 5-6 smaller, nutrient-dense meals throughout the day. This is often more manageable than forcing yourself to eat until you are uncomfortably full.
Use calorie-dense additions: Add healthy fats to meals, such as a tablespoon of olive oil on vegetables, avocado on toast, or nut butter in oatmeal or shakes.
Embrace liquid calories: Smoothies are an excellent way to consume extra calories without feeling stuffed. Blend protein powder, whole milk, oats, fruit, and nut butter for a high-calorie, nutrient-packed shake.
Snack strategically: Don't waste snacking opportunities. Choose calorie-dense options like nuts, dried fruit, Greek yogurt, or cheese to fill the gaps between meals.
Prioritize post-workout nutrition: Consume a meal or shake with protein and carbohydrates within a couple of hours after your workout to kickstart muscle repair and recovery.

Clean vs. Dirty Bulking: A Comparison


Feature	Clean Bulking	Dirty Bulking
Calorie Surplus	Moderate (300-500 kcal daily)	Aggressive (600+ kcal daily)
Food Sources	Nutrient-dense, whole foods (lean proteins, complex carbs, healthy fats)	High-calorie, processed foods, fast food, and sweets
Pace of Weight Gain	Slower and more controlled, maximizing lean muscle gain	Rapid, but includes significant excess fat gain
Fat Gain	Minimal and easily manageable	Substantial, requiring a longer cutting phase
Health Impact	Positive, supporting overall health and hormone function	Potential negative effects on health, energy, and digestion
Sustainability	Creates healthy, long-term habits	Not sustainable; often leads to a cycle of bulking and cutting

Conclusion

For a skinnier person looking to bulk up, the answer is definitively to eat more, but with a strategic and disciplined approach. Instead of a reckless "dirty bulk" that piles on excess fat, a "clean bulk" with a controlled calorie surplus of 300-500 calories is the most effective and healthiest method. By prioritizing a balanced intake of protein, complex carbohydrates, and healthy fats, and fueling your body with nutrient-dense foods, you can maximize lean muscle gains while minimizing unwanted fat accumulation. Consistency in both your nutrition and resistance training is the key to seeing real, sustainable results. For more detailed nutrition plans tailored to muscle-building goals, it can be beneficial to consult with a registered dietitian.

Frequently Asked Questions

A skinny person should aim for a daily calorie surplus of 300-500 calories above their maintenance level. This moderate increase promotes muscle growth while minimizing excess fat gain.

Some people have a naturally higher metabolism, often referred to as ectomorphs. This means their bodies burn through calories faster, requiring a greater, more consistent caloric intake to facilitate weight and muscle gain.

For an ectomorph body type, a recommended macronutrient ratio is typically around 50-60% carbohydrates, 25-30% protein, and 15-25% fats. This prioritizes carbs for energy while providing sufficient protein for muscle repair.

While dirty bulking can lead to rapid weight gain, it results in a larger proportion of fat. A cleaner, more controlled bulk is recommended even for hardgainers, as it promotes healthier, more sustainable muscle gains and avoids a long cutting phase later.

To increase calories, focus on nutrient-rich, dense foods like nuts and seeds, avocados, whole milk, full-fat dairy products, and healthy oils like olive oil. Liquid calories from shakes with protein powder and oats are also effective.

It is not necessary to eliminate cardio entirely, but you may want to limit it to light sessions. Excessive cardio can burn too many calories, making it harder to maintain a consistent surplus for muscle growth.

Protein is the most important macronutrient for muscle growth. It provides the amino acids needed to repair and rebuild muscle fibers. Aiming for 1.6-2.2 grams of protein per kilogram of body weight is key for maximizing muscle gain.