What Should I Eat to Gain Weight? A Guide to a Healthy Nutrition Diet Plan

October 2, 2025 •

5 min read

For some, gaining weight is as much of a struggle as losing it. For instance, according to the Centers for Disease Control and Prevention, approximately 1.6% of US adults aged 20 or older are underweight, highlighting a real and often overlooked health concern. Addressing the question, 'what should I eat to gain weight?', requires a focused approach that prioritizes nutrient-dense, high-calorie foods over empty calories. This guide offers a blueprint for achieving healthy and sustainable weight gain.

Quick Summary

This guide provides a nutritional blueprint for healthy weight gain, focusing on creating a calorie surplus with nutrient-dense foods. It outlines key macronutrients, high-calorie food options, and effective meal strategies for building muscle mass safely.

Key Points

Create a Calorie Surplus: To gain weight, consistently consume more calories than you burn each day.
Prioritize Nutrient-Dense Foods: Focus on high-calorie foods that are also rich in nutrients, such as avocados, nuts, and whole grains, to ensure healthy weight gain.
Increase Protein Intake: Eat plenty of high-quality protein from sources like lean meats, fish, eggs, and dairy to support muscle growth.
Incorporate Healthy Fats: Add calorie-dense healthy fats like olive oil, nuts, and avocados to your meals and snacks for an easy calorie boost.
Eat More Frequently: Aim for 3 meals and 2-3 snacks daily to consume more calories without feeling overly full.
Use High-Calorie Beverages: Drink homemade protein shakes or smoothies between meals to increase your overall calorie consumption.
Combine with Strength Training: Pair your diet with resistance exercises to build muscle mass, ensuring a healthy body composition.

For many, gaining weight, particularly healthy muscle mass rather than fat, is a challenging goal that requires a strategic and consistent approach. The foundation of any successful weight gain strategy is to consume more calories than your body burns—a concept known as a calorie surplus. However, the quality of those calories is just as important as the quantity. The focus should be on energy-dense and nutrient-rich foods that provide the necessary fuel for muscle growth, not just fat storage.

The Three Pillars of a Healthy Weight Gain Diet

1. Prioritize Protein

Protein is the single most important nutrient for building muscle mass. Adequate intake is essential, especially when combined with resistance training. It helps repair muscle tissues damaged during exercise and promotes new muscle growth. Good sources include:

Lean Meats and Fish: Chicken, beef, pork, salmon, and other fatty fish are excellent sources of high-quality protein. Fatty fish like salmon also offer healthy omega-3 fatty acids.
Eggs: A complete protein source, eggs are packed with essential nutrients and are versatile for any meal.
Dairy Products: Full-fat milk, Greek yogurt, and cheese provide a balanced mix of protein, fats, and calcium.
Legumes: Lentils, chickpeas, and beans are fantastic plant-based protein and fiber sources.
Nuts and Seeds: Almonds, walnuts, and flaxseeds are rich in protein and healthy fats, making them ideal for snacks or adding to meals.

2. Don’t Fear Healthy Carbs

Carbohydrates are your body's primary energy source, and complex carbs are crucial for sustained energy during workouts. They also replenish muscle glycogen stores, which are vital for physical activity.

Whole Grains: Oats, brown rice, quinoa, and whole-grain bread are excellent sources of complex carbs and fiber.
Starchy Vegetables: Potatoes and sweet potatoes are calorie-dense and provide important nutrients and fiber.
Fruits: Fruits like bananas, mangoes, and dried fruits are high in natural sugars and calories, providing a quick energy boost.

3. Embrace Healthy Fats

Healthy fats are the most calorie-dense macronutrient, containing 9 calories per gram. Including them in your diet is an easy way to increase your calorie intake without feeling overly full.

Avocados: Rich in monounsaturated fats, avocados can be added to salads, smoothies, or toast.
Nut Butters: Peanut butter and almond butter offer a great mix of healthy fats and protein. Spread them on whole-grain toast or add them to smoothies.
Oils: Olive oil and coconut oil can be added to cooking, dressings, or drizzled over vegetables for extra calories.
Nuts and Seeds: As mentioned earlier, nuts and seeds are a great source of healthy fats.

Meal and Snack Strategies for Weight Gain

Beyond choosing the right foods, how and when you eat can significantly impact your progress. Incorporating these strategies can help you maximize your calorie intake throughout the day.

Eat Frequently: Aim for 3 main meals and 2-3 snacks per day. Eating smaller, more frequent meals can make it easier to consume the necessary calories, especially if you have a smaller appetite.
Boost Your Beverages: High-calorie drinks can help you increase your intake without the bulk of solid food. Try homemade protein smoothies made with whole milk, protein powder, nut butter, and fruit.
Add Extra Calories: Sneak extra calories into your regular meals. For instance, add cheese to baked potatoes, nuts and seeds to oatmeal, or a spoonful of olive oil to cooked vegetables.
Make Smart Snacking a Priority: Always have calorie-dense, nutrient-rich snacks on hand. Trail mix, Greek yogurt with granola, and hard-boiled eggs are great options.
Don't Skip Meals: Consistency is key. Never skip breakfast, as this is a prime opportunity to kickstart your calorie intake for the day.

Comparing Healthy and Less Healthy Weight Gain Options


Feature	Healthy Weight Gain	Less Healthy Weight Gain	Comparison	Importance of a Balanced Approach
Food Choices	Nutrient-dense, whole foods (e.g., avocados, nuts, lean protein).	Processed foods, sugary snacks, fried items (e.g., chips, soda, fast food).	Healthy options provide essential vitamins and minerals alongside calories, whereas unhealthy choices offer 'empty calories' lacking nutritional value.	Prioritizing nutrient-dense options ensures the weight gained is muscle and not just fat, supporting overall health.
Satiety	Good sources of fiber and protein can promote a feeling of fullness, which can sometimes be a challenge for those trying to gain.	Poor satiety, leading to a quick calorie spike but no long-lasting fullness.	High-fiber, whole foods offer better nutritional payoff and prevent rapid drops in blood sugar, while junk food can lead to cravings.	A healthy approach manages appetite better, making it easier to stick to the diet without resorting to unhealthy bingeing.
Health Impact	Builds muscle mass, improves overall health, and supports bodily functions.	Increased risk of health issues like type 2 diabetes and heart disease due to high sugar and saturated fat content.	Focusing on healthy weight gain minimizes the risk of chronic diseases often associated with excessive body fat.	Long-term health should be the priority, and a balanced, whole-food diet is crucial for sustainable well-being.

The Role of Exercise in Weight Gain

Diet and exercise work together to achieve healthy weight gain. While diet creates the calorie surplus, a consistent strength training program directs those extra calories toward building muscle, rather than being stored as fat. Exercises like weightlifting or bodyweight exercises trigger muscle hypertrophy, the process of muscle growth. This synergy ensures that your weight gain is productive and improves your overall body composition. For advice on strength training, resources like the NHS Fitness Studio offer free videos for at-home workouts.

Conclusion

For those asking "what should I eat to gain weight?" the answer is a strategic combination of nutrient-rich, calorie-dense foods and a consistent exercise routine. Focusing on a balanced intake of protein, healthy carbohydrates, and good fats provides the body with the necessary fuel for building muscle mass safely. By incorporating more frequent meals, boosting your beverages, and making smart snack choices, you can effectively and healthily increase your caloric intake. Always remember that healthy weight gain is a gradual process and should be paired with physical activity to ensure the weight is gained as lean mass rather than unwanted fat. Consistency and a well-planned approach are the keys to success.

Expert Consultation

While the advice in this guide can help, individual nutritional needs can vary. It is always recommended to consult a doctor or a registered dietitian, especially if you have underlying health conditions, to ensure your weight gain plan is tailored to your specific needs and is safe for you.

This article is for informational purposes only and does not constitute medical advice.

Frequently Asked Questions

For healthy, steady weight gain, adults can aim to add around 300 to 500 extra calories per day to their diet. For faster weight gain, this can be increased to 700 to 1,000 extra calories, but this should be done in consultation with a professional.

It is generally healthier and more sustainable to gain weight gradually. Rapid weight gain is more likely to result in fat accumulation rather than muscle mass, and can increase the risk of other health problems.

Great high-calorie and healthy snack options include trail mix with nuts and dried fruit, Greek yogurt with granola, whole-grain toast with peanut butter and banana, and homemade protein smoothies.

While junk food is high in calories, it lacks essential nutrients and can lead to unhealthy fat gain and an increased risk of chronic diseases. Focusing on nutrient-dense foods is crucial for safe and healthy weight gain.

Protein shakes can be a convenient way to boost your protein and calorie intake, especially for those struggling to meet their needs through whole foods alone. However, they are not strictly necessary if you can get enough protein from your regular diet.

If you have a small appetite, try eating smaller, more frequent meals throughout the day. Focus on calorie-dense foods, use high-calorie beverages like smoothies, and add extra calories to your meals with ingredients like nuts, seeds, and oils.

Strength training is vital for healthy weight gain as it helps ensure that the extra calories you consume are directed towards building lean muscle mass rather than being stored as body fat. Resistance training promotes muscle growth and improves overall body composition.