Vitamin/mineral deficiencies on a low-calorie diet

I tracked my food intake this past Tuesday. It was an oppressively hot day (96 degrees), so I didn't eat much - only 1511 calories! (Under the traditional 4/9/4 formula, I consumed 1580 calories.) While I did get enough fiber (44.9 grams), I was short on Vitamin K (45% of my target). If it hadn't been for my zinc supplement, I would have come up short there, at only 82% of my target. If it hadn't been for my Vitamin B complex supplement, I would have come up short on pantothenic acid (Vitamin B5), at just 83% of my target.

Even in summer, I normally eat a few hundred calories more per day, and that makes it easier to meet my vitamin and mineral targets. On a bitterly cold day back in February, I consumed about double the calories that I consumed this past Tuesday.

I realize that I came up way short on Vitamin K because I didn't consume broccoli or Brussel sprouts. The vegetables that I did eat on Tuesday weren't that high in this nutrient.

Because I eat much less food overall in summer compared to winter, the variety I consume is less. Because I eat more vegetables in winter (simply because I'm eating more food overall), it's easier to eat a variety.

My questions:
1. How do people on low-calorie diets get enough vitamins and minerals without relying on supplements? While my deficiencies on Tuesday were a one-off, this wouldn't be the case if I were deliberately limiting my calories.
2. How do people who live in places with oppressively hot weather get enough vitamins and minerals? Since I live in the Twin Cities, MN, weather as oppressively hot as Tuesday's weather is rare. Temperatures in the mid-90s or higher are the norm in places like Tulsa, Oklahoma City, Dallas/Fort Worth, Austin, San Antonio, El Paso, Fresno, Palm Springs, Phoenix, Tucson, Las Vegas, and Yuma. Places like New Orleans, Miami, Tampa, and Orlando aren't nearly as hot but easily make up for it with excessive humidity. If I lived in one of these places notorious for oppressive summer heat, I might end up with some nutritional deficiencies simply because my small appetite limits my consumption of some nutrients.


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    Happy to answer your questions from the perspective of a dietitian. As incredible as Cronometer is, there are some limitations to its use including user error (which encompasses accuracy of amount consumed, correct brand, loss to cooking/preparation, etc.) and database limits. If nutrient information is being pulled from a label, the food should ideally be cross-referenced to determine it's complete nutrient profile.

    The other thing to keep in mind is that deficiencies don't develop over a day... Your body has a number of processes in place to enhance absorption when intake is low (such as with iron). If tracking was completely accurate (which is difficult to do outside of a laboratory setting), I wouldn't consider someone at risk of deficiency unless I had at least a month of data to look at (sometimes more).

    All this to say, if you're curious about your risk of deficiency, I would a) track as accurately as possible and b) not make any decisions until you have several months of data for reference. Taking this info to a dietitian could also be useful as the database just can't track some nutrients well, such as iodine.

    I live in Canada where our temperature swings from -40 to +40 within the same year (I work in Celsius!). This takes some major acclimatization and like you, my appetite can change based on the weather. However, individuals who live in consistently cold or hot climates are already acclimatized to the weather and less likely to experience such fluctuations in appetite. Anecdotally, I also find that there is a lot of individual variation in how much appetite is impacted by weather.

    Hope this helps!

    Susan Macfarlane, MScA, RD
    Registered Dietitian Nutritionist
    As always, any and all postings here are covered by our T&Cs:

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    Thanks, Susan! I know that the information in the NCCDB database is more comprehensive than the information in other databases. Does the NCCDB have limitations as well? Is it common for foods to have Vitamin B5, Vitamin K, zinc, etc. despite not being listed as such in the NCCDB database?

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    Note that any packaged food will almost always have only the nutritional information legally required by the government - calories, protein, fat, carbs, and fibre. At most they'll have something else if they're trying to promote it as "healthy", eg low sugar, high iron, whatever.

    As well, even for single-ingredient foods like raw meat, fish, etc, there'll often be information missing if it's not a super-common food. For example I eat a bit of kangaroo, iron is listed but not zinc - when I went looking I found it does indeed have zinc like all red meat will, they just didn't think it was important to list on the label.

    As Susan said, look at your averages over time. If failing to get enough vitamin K (for example) on a single day were deadly, the human race would be extinct by now. If I'm at 50% for 6 days and then 400% on the 7th, it's going to balance out to a nice even 100% for the past week.

    As for eating in the heat, the places you list like Florida have a lot of obese people, so obviously people do manage to eat something or other, the only question is what. You're evidently a person who doesn't have a big appetite naturally.

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    Thanks, Susan and Kiashu!

    Am I the only one who doesn't eat much in hot weather? It is so baffling that there can be so many obese people in places known for oppressive heat. Then again, I'm not one of those people who look forward to summer all year long and then deep-freeze themselves when it finally arrives. During air conditioning season, my idea of room temperature is 80 degrees. In winter, my idea of room temperature is more like 55 to 60 degrees.

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    It is so baffling that there can be so many obese people in places known for oppressive heat.

    It's worth noting that there were few obese people in tropical and sub-tropical regions on the traditional diet. It's only after we introduced them to the standard American/western diet that obesity became a problem.

    And of those who live in hot climates are going to be those best adapted to the weather. If their ancestors couldn't eat on hot days, they would have died out millennia ago.

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    edited May 2023

    When following a low-calorie diet, it's important to be mindful of potential vitamin and mineral deficiencies that can occur due to the restricted intake of food. Here are some common nutrients that may be at risk of deficiency on a low-calorie diet:

    Vitamin B12: This vitamin is mainly found in animal-based foods, so individuals following a low-calorie vegetarian or vegan diet may be at risk of deficiency. It's recommended to consider supplementation or consume fortified foods to meet your B12 needs.

    Iron: Iron is essential for oxygen transport in the body. Since low-calorie diets often limit red meat and other iron-rich foods, it's important to ensure adequate intake through alternative sources like leafy greens, legumes, fortified cereals, and iron supplements if necessary.

    Calcium: Dairy products are typically restricted in low-calorie diets due to their calorie content. Calcium deficiency can be a concern, so it's essential to include other calcium-rich sources like fortified plant-based milk, leafy greens, tofu, and calcium supplements if needed.

    Vitamin D: Sunlight is a primary source of vitamin D, but if you have limited sun exposure or are following a low-calorie diet that lacks vitamin D-fortified foods, supplementation might be necessary to maintain adequate levels.

    Omega-3 fatty acids: Low-calorie diets may restrict high-fat foods like fatty fish, nuts, and seeds, which are rich in omega-3 fatty acids. Including alternative sources like flaxseeds, chia seeds, or algae-based supplements can help prevent deficiencies.

    Zinc: Zinc plays a vital role in immune function and metabolism. It can be found in animal-based and plant-based protein sources, so it's important to incorporate a variety of protein-rich foods into your low-calorie diet.

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