Nutrients play a significant role in maintaining a healthy body. But how do we know if we are deficient? And can a deficiency have an impact on body composition? Our scientific contributor, Heather Huntsman Ph.D., CSCS, provides insight into the link between nutritional deficiencies, body composition, and maintaining overall health.
Are You Nutrient Deficient?
The topic of nutrient deficiencies seems like it should be fairly straightforward, but it can get complicated. In the United States, we have recommended daily allowances (RDAs) (also referred to as dietary reference intakes) for each essential nutrient that is issued by the Food and Nutrition Board of the Institute of Medicine. RDAs state the adequate levels of each nutrient needed for practically all healthy people, and are largely based on observation and a handful of detailed nutrient balance studies.1 These values are also used to calculate the percent daily values that are printed on every food label in the grocery store. Unlike packaged foods, we don’t have nutrient labels slapped on our backs to give us a sense of what we might be deficient in. So, how do you actually know if you are getting all of the nutrients you need? This is where the things get a lot more complicated. The answer to that question: it depends.
First of all, an incredibly important aspect of this answer is factors like age, sex, activity level, and life cycle stage (e.g. adolescence, during pregnancy, etc.) and how they all affect RDAs.2 For instance, men and women do not have the same nutrient requirements, and children and pregnant and lactating women require different levels of key vitamins to support their growth.3 If you are training for an ironman, then you will likely need more calories and antioxidants to support the increased demands placed on your body. In the end, percent daily values printed in every food label are not accurate for all people simply because we all have different needs at a given time in life.
Secondly, whether or not you are getting adequate amounts of all the nutrients depends on the nutrient in question.1 For some nutrients like the 3 macronutrients (carbohydrates, protein, and fat), it only requires a few weeks to know whether or not your intake falls within appropriate ranges. For example, you can be high in fat on one day and low the next, but it is the average over time that matters. Unfortunately, not all nutrients are metabolized and stored in the same way. This impacts the timeframe needed to monitor for an accurate picture of average intake. Vitamin A, a fat-soluble vitamin is a great example of this concept. A study done in healthy participants suggests that it could take as long as a year to accurately assess whether you are consuming enough vitamin A.1 That is long time to monitor everything you eat. In the short-term, listening to your body may be a good place to start to determine if you are deficient in any major nutrient group. Are feeling more tired than usual? Do you notice your skin doesn’t look as bright as is used to, or you seem to be getting little pesky infections more often? If so, you can suspect it may be related to nutrition and you can discuss options with your doctor. Regular check-ups and blood work is a good place to start examining nutritional deficiencies.
Nutrient Deficiencies & Body Composition
By now, you may start to understanding just how complex the question around nutrient deficiencies is. What’s even more perplexing is the potential impact of nutrient deficiencies on body composition. There is no black and white answer, but there are two important concepts that are foundational to understanding the importance of preventing deficiencies to optimize health, and by extension, body composition.
One explanation, discussed in previous posts, is that each nutrient, both macro and micro, plays a role in the health and proper functioning of different tissues and systems in your body. For example, omega-3 fatty acids appear to contribute to heart health, and calcium and vitamin D are important in bone health. Both of these are essential to building and maintaining a healthy body composition. However, as stated previously, RDAs are largely based on observation and a small number of detailed studies. So, as much as I’d like to tell you that focusing on vitamin D or eating a low-fat diet will help you optimize your body composition, the data just aren’t there to apply to every person.3-4
A sure bet, however, is eating a well-balance diet to minimizing deficiencies and optimizing health. While there are a lot of nutrients to consider, the best advice I can give you is to be mindful about the diversity of foods in your diet. Eat all the colors of the rainbow, try new things, be aware of your portion sizes, take a daily multivitamin (if your doctor recommends one) and maybe even keep a food journal to stay mindful about what you are consuming.
Remember, your body is a very complex machine with several systems acting in concert. The best thing you can do for your overall health is to fuel your body with a diversity of nutrients in a balanced and consistent manner. Doing so will improve the function of each system, metabolism included, and will in-turn help maintain muscle mass and minimize fat storage.
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