One of the most common questions personal trainers receive from clients is, “What should I eat?” With several competing dietary philosophies all claiming superiority when it comes to health outcomes, there is a common theme they all share: replacing empty calories with nutrient-dense whole foods. 

Empty calories are foods that supply a high amount of energy, but provide little to no vitamins, minerals, or antioxidants.

Nutrient density refers to the amount of vitamins and minerals (micronutrients) in a food relative to the number of calories in that food. A nutrient-dense food provides a high amount of micronutrients per calorie of that food.

[sc name=”resistance” ][/sc]

Which Foods Are Most Nutrient-Dense?

It will come as no surprise that fruits and vegetables are the most commonly consumed nutrient-dense foods. They are low in calories per serving, and provide vitamins, minerals, antioxidants, fiber, water, and other phytonutrients (beneficial compounds found in plants that are neither vitamins or minerals).

However, when it comes to the highest amount of micronutrients per calorie, the kings of nutrient density are organ meats, herbs and spices, and seafood, particularly mollusks.

Introduction to Organ Meats

Organ meats – also referred to as offal (pronounced “OH-full”), or the “nasty bits” – commonly used in cuisine are heart, liver, kidney, bone marrow, and sweetbreads, and can also include cheeks, tripe, and tongue. While the idea of consuming an animal’s guts may sound off-putting, they have traditionally been staples in the diets of a multitude of cultures for generations.

Menudo, pho, osso bucco, turkey giblet gravy, chitterlings, pâté, and foie gras are all derived from organ meats. From a sustainability perspective, eating organ meat results in less food waste. The culinary world has embraced this “nose to tail” concept as well, with a number of chefs awarded Michelin stars for their cuisine that includes dishes featuring organs. Organs are not only nutritious but can also be delicious, especially when seasoned with herbs and spices.

  • Liver is rich in Vitamin A, riboflavin, thiamine, Vitamin B12, choline, biotin, folate, copper, zinc, selenium, phosphorus, and iron.
  • Heart is a good source of thiamin, Vitamin B6, pantothenic acid, phosphorus, copper, riboflavin, niacin, Vitamin B12, iron, CoQ10, and selenium.
  • Kidneys are loaded with vitamin B12, iron, riboflavin, vitamin B6, folate, and niacin.
  • Bone Marrow, while high in calories, abounds with collagen, glycine, glucosamine, and conjugated linoleic acid.
  • Sweetbreads are neither sweet nor bread. It is an umbrella term that encompasses the thymus and pancreas, and can also include the parotid glands and sublingual glands. Sweetbreads are excellent sources of Vitamin B12, pantothenic acid, phosphorus, selenium, and Vitamin C.

Herbs, Spices, Mollusks

Fresh herbs and spices enhance more than the flavor of your food.  They enhance the micronutrient content for a very small number of calories.  They also contain myriad phytonutrients. Here are some common examples:

  • Rosemary is rich in iron, copper, magnesium, manganese, calcium, Vitamin A, Vitamin C, folate, and Vitamin B6
  • Thyme is high in Vitamin C, iron, magnesium, calcium, copper, manganese, and riboflavin
  • Oregano is an excellent source of calcium, iron, magnesium, zinc, copper, Vitamin E, Vitamin K, and folate.
  • Black pepper delivers high concentrations of calcium, iron, magnesium, zinc, Vitamin K, copper, and manganese
  • Cumin contains high amounts of iron, magnesium, calcium, potassium, and zinc.
  • Paprika is an abundant source of iron, Vitamin E, Vitamin K, zinc, copper, and manganese

Mollusks are a subcategory of shellfish, and they include clams, oysters, scallops, mussels, and some species of snails, squid, and octopus.

  • Clams, oysters, and mussels are excellent sources of riboflavin, niacin, potassium, zinc, Vitamin C, Vitamin B12, iron, phosphorus, copper, manganese, and selenium
  • Scallops are rich in Vitamin B12, calcium, iron, magnesium, potassium, zinc, copper, phosphorus, and selenium.
  • Snails have high amounts of potassium, Vitamin E, iron, magnesium, phosphorus, copper, and selenium.
  • Squid and octopus are rich sources of niacin, zinc, riboflavin, Vitamin B12, phosphorus, copper, and selenium.

Why is Nutrient-Density Important?

Vitamins and minerals are the essential chemicals responsible for many of the metabolic processes in the body. Consuming a diet high in nutrient-dense foods often leads to better health outcomes as it gives the body the raw materials needed to execute it functions optimally. Many chronic conditions, including mood disorders, have been caused by or linked to nutritional deficiencies.

Humans’ sense of taste evolved as a way to detect the nutrient content of any given food, and as a protective mechanism against potentially lethal pathogens. In this evolutionary context, food tasted good because of the vitamins and minerals they contained in addition to the energy they provided.

Before the industrialization and modernization of our food supply, food that contained a substantial number of calories was accompanied by a commensurate amount of vitamins, minerals, and antioxidants. In our modern food environment, those taste signals are easily overridden by the hyper-palatable, calorically-dense convenience foods that many individuals utilize as staples of their diet.

The nutrient content of the majority of the standard American diet does not justify the calorie load. Novel combinations of flavors created by food companies far outshine what is available from nature. The result is a population that continues to gain weight and become sick from their lifestyle and diet choices because humans are hardwired to choose foods based on flavor.

Talking to Your Client

When advising a client on nutrition, it’s almost always a safe bet to advocate for greater consumption of vegetables and fruits. One of the key factors for a client becoming healthier is improving their nutrient status. Swapping out something manufactured for something that was grown can get them to realize that whole foods have more to offer than just low calories.

For those clients who are more adventurous, encouraging them to try some of the nutrient-dense foods mentioned in this article can be a fun way to spice up (literally) their diet routine.  Some may even find a new favorite food that they may not have considered otherwise.  

As trainers, we have a unique relationship with our clients.  We can help them grow more than just their muscles.  Helping them find new ways to enjoy a healthy lifestyle, like trying a new food that’s packed with vitamins and minerals, can lead to them adopting other new healthy behaviors.

Nutrition Specialty Banner (1)


An Evolutionary Perspective on Food and Human Taste. (2013, May 06). Retrieved from

Butcher Magazine Team. (2019, February 11). What Is Offal? A Guide To Nutritious Organ Meat. Retrieved from

Dong, F. M. (n.d.). The Nutritional Value of Shellfish. Retrieved from, Q., Shen, T., Wang, F., Wu, P., & Chen, J. (2018, February). 

Preventive and Therapeutic Potential of Vitamin C in Mental Disorders. Retrieved from Health Publishing. (n.d.). 

Understanding empty calories. Retrieved from, J., Um, P., Dickerman, B. A., & Liu, J. (2018, May 09). 

Zinc, Magnesium, Selenium and Depression: A Review of the Evidence, Potential Mechanisms and Implications. Retrieved from

Welcome to the USDA Food Composition Databases. (n.d.). Retrieved from

David Rodriguez

David Rodriguez is a graduate of the Personal Trainer Certificate Program at San Diego Mesa College, an NFPT and ACE Certified Personal Trainer, and Certified Fitness Nutrition Specialist. David was inspired to become a personal trainer after losing more than 100 pounds. Having kept the weight off for over a decade, he uses his story to motivate his clients and demonstrate to them that big changes are possible and sustainable. His training focuses on pain-free movement, helping clients find an individualized nutrition plan, and creating a positive mindset. His favorite pastimes are soccer, weightlifting, hiking, cooking, and his dogs. David lives in San Diego.