During my SIBO journey, I failed to adequately nourish my body. The fear of feeding the SIBO caused me to unintentional under eat. When I transitioned to a lower carb whole foods diet, I also didn’t understand how much I needed to up my fat intake to meet my needs.

I also wasn’t digesting and absorbing properly due to the gut inflammation and imbalance. The under-eating and the poor absorption resulted in uncontrollable weight loss. I felt weak and depleted.

I see a similar trend of under-eating in my clients. About 75% of my clients are under-eating when they come to me. Many have jumped on a restrictive diet making it harder to get the necessary nutrients in. Others struggle to eat enough because their symptoms are so bad, but this often backfires, because failing to nourish your body will often make symptoms much much worse.

With our thin centric diet culture, it can be very easy to under eat, especially for women. Health conscious woman have been pre-programmed to try to cut calories whenever possible. The marketing of low calorie snacks/meals in magazines, commercials and food packaging plants the idea that the fewer calories we eat the better.

And to be fair, many Americans eat a standard American diet filled with Twinkies, Doritos and other high calorie, nutrient poor options. With obesity on the rise, many Americans may need to be more cognizant of their calorie intake.

But in my opinion, Americans with poor diets would be able to regulate calories so much better if they switched to a primarily whole foods diet instead of a low calorie Twinkie! But, that is an argument for a different day!

When eating lower calorie is pervasively promoted as a healthy way to eat, it can be easy to underestimate how much food you actually need to stay nourished. Our society already sets us up to fail.

When you throw in restrictive SIBO diets, these make it even easier to under eat. I failed to see that I needed more calories during my SIBO journey, because I felt like my meals were adequate. But, they were not.

In reality, I was probably under-eating by 300-400 calories a day (eating around 1500-1600 calories). This calorie deficit isn’t super extreme, but over time can lead to hormonal imbalances, nutrient deficiencies and blood sugar swings (all of which will negatively effect gut function). As I mentioned above, many of my clients are in a similar predicament.

My first priority when I work with clients is to ensure adequate intake of calories. You can not heal from SIBO if you are not consuming the nutrients your body needs. SIBO and other gut issues can even be caused by chronic dieting and under-eating.

Weight can be deceptive

Weight loss is the most commonly used indicator for under-eating. You may be rolling your eyes right now thinking “thank you, captain obvious”, but with gut issues it isn’t entirely cut and dry. You may be eating enough calories, but failing to optimally digest and absorb the nutrients leading to weight loss.

To make matters even more confusing, under-eating can slow your metabolism. Therefore, your weight may stay the same or even increase even if you are under-eating. This down shift in metabolic function is a result of 2 key mechanisms.

First, under-eating increases cortisol levels. Second, under-eating reduces thyroid function. These shifts are probably an adapted response to low energy. With fuel low, your body wants to conserve it’s limited resources.

This downward metabolic shift is often seen in chronic dieters.  Studies have shown that calorie restricting and chronic dieting reduces metabolism by as much as 25%!

The big takeaway is that your weight can often be deceiving when it comes to diagnosing under-eating. You must also analyze your caloric intake and your symptoms to confirm under-eating.

Symptoms of Under-eating

I often look for signs of under-eating when I work with clients. Luckily, I have spent the last 2 years learning from Laura Schoenfeld, a holistic dietitian with a passion for helping under eaters find their way back to health! I had the pleasure of working under Laura while I was in school and she has taught me a lot about the negative health consequences of chronic under-eating!

I highly recommend checking out this article that Laura wrote for Chris Kresser’s website that details 8 signs of under-eating. Here are the signs that Laura links to under-eating:

  • Amenorrhea, irregular periods and infertility
  • Blood sugar swings
  • Unpredictable moods
  • Can’t fall asleep or stay asleep
  • Chronic constipation
  • Cold hands/feet
  • Hair Loss
  • Failing to lose weight (if you are trying)

I am happy that chronic constipation made her list of signs and symptoms. GI dysfunction will result from chronic undereating. GI symptoms generally get worse if you are chronically running on empty.

Check out this diagram that lays out how undereating causes more gut dysfunction:

Undereating and gut function
Shit hits the fan when we under eat….literally

How many calories do I need?

Consistently achieving adequate intake is critical to healing. Even if you may have some weight to lose, during SIBO treatment is not the right time to cut calories since your body is already stressed from gut dysfunction the SIBO is causing.

Your body will tolerate a calorie deficit much better when your gut is healthy. Table weight loss goals for down the road.

But, with our societies focus on low calorie equaling healthy, it can be easy to underestimate the amount of calories you may need. Just because a Cosmo magazine told you 1500 calories a day was a good goal doesn’t mean it is the right goal for you!

The biggest determiners of how many calories you need is your age, your sex and the amount of physical activity you do. I love using this calorie estimator from Laura Schoenfeld’s website. This calculator can give you a good estimation on how many calories you should be getting based on your age, sex and physical activity. It is not perfect, but is a great place to start.

If you don’t count calories, you may have no idea how many calories that you are consuming. You may feel like your meals are adequate, but you could be missing the mark.

I see many clients unintentionally under-eating, especially after switching to a more low carb, restrictive diet. Many replace bread with lettuce wraps or spaghetti with zucchini noodles. The lettuce and zucchini have much fewer calories than their starchy counterparts.

These calorie deductions can really add up throughout the day. Some SIBO sufferers might do better on a lower carb diet, but they need to make sure that they are replacing their lost carb calories with more healthy fats.

I also see a lot of SIBO sufferers limiting their feeding windows through intermittent fasting. By eating only 2 meals a day or only eating in a 6 hour window, you may unintentionally lower your caloric intake. It is important to increase the amount of food you are eating to compensate for a shorter eating window.

If you have some symptoms of undereating and are not sure if you are getting enough calories, then you may need to track your calories to better understand if you are hitting your calorie target. You don’t need to track every day, but tracking for 3 days to get a baseline of what your usual intake level is can be very helpful.

I like the cronometer app for tracking calories because I find it simple and easy to use. If your calorie intake is less than your estimated calorie needs, then you should up your calories. By continuing to under eat, you could be making your gut problems worse.

If you are eating enough calories but losing weight, then you may have malabsorption issues to work through. Digestive enzymes may be a necessary step to help optimize nutrient absorption while you heal and repair breakdowns in the gut.


Tips to help increase calories!

Add some carbs back in

When you cut out carbs it can be easy to under eat calories, because you need to eat a lot more fats to nourish your body. Carbs can also be really important for optimizing hormones like cortisol and thyroid hormones. Balancing out your meals with more carbs can help you hit your calorie target.

If you struggle with volume of whole foods carbs, you could try adding some maple syrup or honey to dishes

When you first switch to a whole foods diet, the volume of food needed to meet your needs may be surprising. It can take some time for your body to adjust. Adding some lower volume foods to add some extra calories to your meals without adding tons of bulk can be helpful during this transition. Maple syrup can be a great addition to dishes that can add some extra calories without the volume.

Add an extra TBSP of fat at each meal

As I mentioned before, it can be hard to transition to a higher volume of foods, especially if you are struggling with carbohydrates. A TBSP of fat has about 120-140 calories. If you add an extra tablespoon to each meal, this can help you up your calorie intake by around 400 calories a day.

Eat bigger portions (especially if you are fasting)

If you are used to being a grazer and snacking between meals, you can easily under eat if you switch to eating 3 meals a day or intermittent fasting. You have to up your portion sizes as the frequency of your meals/snacking decrease.

Add in a snack if necessary

While limiting meal frequency can be helpful for MMC function, some of my clients do better adding a snack in to help them get enough calories in. Adding in a snack may be especially important for those that are having blood sugar swings and cortisol dysregulation.

Work with a practitioner

If you are under-eating, losing weight or not absorbing food, working with a knowledgeable practitioner is very helpful. A practitioner can analyze your intake, weight and symptoms and come up with an action plan to address under-eating or malabsorption.


Bottom Line

You can not heal your gut if your body is starving for nutrients. If you suspect you are under-eating, track your calories and see where you stand. Resolving under-eating can have a positive effect on gut function!

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