What to drink if underweight? Discover the best high-calorie beverages for healthy weight gain

October 10, 2025 •

4 min read

According to the World Health Organization, being underweight is a real issue affecting millions globally, making intentional, healthy weight gain crucial for many individuals. For those with a diminished appetite, integrating liquid calories into your diet is a highly effective and less overwhelming strategy, making understanding what to drink if underweight a key part of your nutrition plan.

Quick Summary

Integrating calorie-dense beverages into your diet is a simple method for increasing overall calorie intake to support healthy weight gain. Focus on nutrient-packed drinks like homemade shakes, whole milk, and smoothies that combine protein, healthy fats, and carbohydrates for maximum nutritional benefit.

Key Points

Prioritize liquid calories: Use nutrient-dense drinks like smoothies and shakes to increase calorie intake easily, especially if you have a low appetite.
Focus on balanced ingredients: Combine a source of healthy fats (nut butter, avocado), protein (Greek yogurt, protein powder), and complex carbs (oats, bananas) for maximum nutritional benefit.
Choose whole milk over skim: Opt for full-fat dairy products like whole milk, full-fat yogurt, and cheese for a higher calorie count.
Don't forget protein supplements: Consider adding whey or casein protein powder to increase protein content, especially if you are combining weight gain with resistance training.
Stay hydrated with water: While calorie-dense drinks are important, continue to drink adequate water to support overall health, metabolism, and nutrient absorption.
Customize for variety: Experiment with different fruits, nuts, and dairy or dairy-free bases to prevent taste fatigue and ensure a consistent routine.

The Role of Calorie-Dense Drinks in Healthy Weight Gain

For individuals looking to gain weight, increasing calorie consumption beyond what the body burns is essential. However, this can be challenging, especially for those with a fast metabolism or a naturally small appetite. This is where nutrient-dense beverages become an invaluable tool. Liquid calories offer a concentrated source of energy that is often easier to consume than large, solid meals, helping to avoid the feeling of being uncomfortably full. These drinks can be strategically incorporated throughout the day as snacks, additions to meals, or even meal replacements.

Prioritizing Nutritious Choices

It is important to remember that not all high-calorie drinks are created equal. Opting for nutrient-rich options over those with empty calories, such as sugary sodas, is critical for healthy and sustainable weight gain. A balanced drink will provide a combination of macronutrients, including healthy fats, complex carbohydrates, and high-quality protein, along with essential vitamins and minerals.

Top Drink Choices for Underweight Individuals

Here are some of the best beverages to include in your diet for healthy weight gain:

Whole Milk and Dairy Products: Whole milk is a classic weight-gainer, offering a balanced mix of proteins, carbs, and fats, along with calcium and vitamins. You can also add full-fat yogurt, cream, or milk powder to increase the calorie count of other drinks.
Homemade Smoothies and Shakes: Customizable and nutrient-dense, homemade shakes can be packed with calories. Key ingredients often include whole milk, nut butters, oats, bananas, and protein powder. Freezing fruit beforehand can give your shake a thicker, ice cream-like consistency.
Nutritional Supplements: For those who struggle to meet their calorie goals, ready-to-drink supplements like Boost® or Ensure® can provide a convenient, concentrated source of nutrition. Some products are specifically designed to be high-calorie to support weight gain.
Fruit Juices and Nectars: While high in natural sugars, 100% fruit juice provides a good calorie boost and can be used as a base for smoothies. Avoid sugary "juice drinks" and opt for pure juice varieties.
Avocado Juice or Shakes: Avocados are rich in heart-healthy fats and calories. Blending them into a shake with ingredients like milk and protein powder offers excellent nutrition and a creamy texture.

Creating Delicious Homemade Weight Gain Shakes

Making your own shakes is a great way to control ingredients and customize flavors. Here are a few ideas to get you started:

Classic Peanut Butter Banana Shake

This is a favorite for a reason, providing a great balance of carbs, protein, and fats.

1 ripe banana
2 tablespoons of peanut butter
1 cup of whole milk
1 scoop of whey protein powder
1/2 cup rolled oats (for extra carbs and fiber)
Blend until smooth and enjoy. For a colder shake, use a frozen banana.

Chocolate Avocado Smoothie

For a decadent treat, this smoothie offers a powerful boost of healthy fats and antioxidants.

1/2 ripe avocado
1 cup whole milk or coconut milk
1 banana
1 tbsp cocoa powder
1 tsp honey (optional)
Blend and serve immediately for a rich, creamy drink.

Tropical Mango Coconut Shake

This dairy-free option is packed with calories and flavor.

1 cup frozen mango chunks
1 cup full-fat coconut milk
1/2 cup full-fat Greek yogurt (or a vegan alternative)
1 tbsp honey
Blend until creamy and smooth. You can add some chia seeds for extra nutrients.

Comparison of High-Calorie Drink Bases

To help you choose the best base for your needs, consider the following comparison:


Drink Base	Calories (approx.)	Protein Content	Key Nutrients	Best For...
Whole Milk	High	Medium	Calcium, Vitamin D, Protein	Everyday use, classic shakes
Full-Fat Greek Yogurt	High	High	Probiotics, Protein	Thickening smoothies, high-protein recipes
Nut Butter	Very High	Medium	Healthy Fats, Magnesium	Boosting calories significantly
Protein Powder	Varies	Very High	Protein	Muscle building, post-workout
Coconut Milk (Full-Fat)	Very High	Low	Healthy Fats (MCTs)	Vegan/dairy-free options

Staying Hydrated and Gaining Weight Safely

Beyond incorporating high-calorie beverages, remember that water is still crucial for overall health and bodily function. Proper hydration supports metabolism, nutrient absorption, and post-workout recovery, all of which are vital for healthy weight gain. A common mistake is to replace water entirely with calorie-dense fluids, but the best approach is to add these shakes and smoothies into your routine alongside regular water intake. Always consult a healthcare professional or registered dietitian before making significant dietary changes, especially if you have underlying health conditions or are looking to gain weight rapidly. A balanced approach that combines calorie-rich drinks with whole foods and an active lifestyle will ensure you achieve your weight goals in a healthy, sustainable way.

For more information on nutrition for weight gain, see the guidelines from the Mayo Clinic.(https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/expert-answers/underweight/faq-20058429)

Frequently Asked Questions

No, drinking water is not bad for weight gain. While it has no calories and can make you feel full, proper hydration is essential for a healthy metabolism and nutrient absorption, both of which are crucial for gaining weight safely.

Yes, ready-to-drink nutritional supplements like Boost® Very High Calorie are designed for weight gain and can be a convenient way to boost your calorie intake. Always check the label to ensure they fit your specific needs.

Whole milk is the best choice for weight gain, as it contains more calories, fat, and protein compared to skim or low-fat milk. You can also fortify it with milk powder for an extra boost.

High-calorie drinks are beneficial for those who are underweight or have increased energy needs. However, for most people, a balanced diet with whole foods is recommended. If you have a health condition, consult a doctor or dietitian.

Good dairy-free options include smoothies made with full-fat coconut milk, soy milk, almond milk, avocado, nut butters, and vegan protein powder to ensure adequate calorie and nutrient content.

You can drink high-calorie shakes one or more times per day, typically between meals or as a post-workout snack. Consistency is key, and aiming for 5-6 smaller meals or snacks a day, including your shakes, can be effective.

Yes, 100% fruit juice can serve as a calorie-dense base for smoothies. While it contains natural sugars, it also offers vitamins and can be a good way to add calories. It's better than fruit-flavored beverages with added sugars.