When we think about weight gain, we often assume it’s just a matter of eating more calories. But for many people, the challenge of being underweight or struggling to maintain a healthy weight is less about how much they eat and more about how well their body can absorb nutrients from food. Poor digestion and nutrient malabsorption can make it difficult to gain weight, while also potentially causing problems with mood, energy levels, and mental well-being.
The digestive system breaks down food and extracts essential nutrients. If digestion is compromised, you may eat enough but still struggle to gain weight because your body isn’t absorbing what it needs.
One common issue is low stomach acid (hypochlorhydria). Stomach acid is essential for breaking down proteins and for absorbing minerals. When stomach acid levels are too low, food isn’t properly digested, leading to malabsorption of iron, zinc, and amino acids. These nutrients that are vital for muscle growth, metabolism, and overall weight maintenance.
Another potential contributor is inflammation in the gut which can damage the intestinal lining. If the gut lining is damaged, this can lead to undigested food particles and bacteria entering the bloodstream, triggering immune reactions and further impairing nutrient absorption. Over time, gut dysfunction can develop which contributes to weight loss, bloating, and food sensitivities.
Gut dysbiosis, an imbalance in gut bacteria, can also contribute to problems gaining weight. The gut microbiome is responsible for breaking down food and producing essential vitamins. If there is an overgrowth of harmful bacteria or a lack of beneficial bacteria, digestion suffers.
Additionally, pancreatic enzyme deficiencies can prevent the proper breakdown of fats, proteins, and carbohydrates, further limiting the number of calories and nutrients absorbed from food. Similarly, conditions like small intestinal bacterial overgrowth (SIBO) can cause malabsorption by interfering with the small intestine’s ability to digest food properly.
Being underweight due to malabsorption can have far reaching effects on mental well-being, particularly anxiety, depression, and cognitive function.
Nutrient deficiencies caused by poor absorption can have a direct impact on brain chemistry. Zinc and magnesium, for example, are essential for nervous system regulation. When levels are low, the body struggles to manage stress, leading to increased anxiety. B vitamins, particularly B12 and folate, play a crucial role in neurotransmitter production, and deficiencies are commonly associated with mood instability and low energy. Amino acids from protein, which serve as the building blocks of neurotransmitters like serotonin and dopamine, can also be lacking if digestion is impaired. This can result in mood swings, low motivation, and difficulty coping with stress.
Additionally, malabsorption of omega-3 fatty acids, which are essential for brain function and managing inflammation, can contribute to cognitive fog, depression, and increased anxiety.
When the body struggles to maintain weight due to malabsorption, it often enters a state of chronic stress, which keeps the nervous system in “fight-or-flight” mode, further exacerbating anxiety and making it even harder for the body to heal and absorb nutrients properly.
For those who struggle with being underweight, mood imbalances, and persistent digestive symptoms, stool testing can be a useful tool. Unlike basic blood tests, stool analysis provides direct insights into how well the digestive system is functioning.
A comprehensive stool test can reveal imbalances in gut bacteria, showing whether there is an overgrowth of harmful bacteria or a lack of beneficial strains that help with digestion. It can also detect the presence of parasites, yeast overgrowth or markers of inflammation, all of which can contribute to malabsorption.
Additionally, stool testing can assess enzyme function by measuring markers like pancreatic elastase, which indicates how well the pancreas is producing digestive enzymes. If enzyme levels are low, food is not being properly broken down, making it difficult for the body to extract essential nutrients.
Markers of fat malabsorption are also evaluated in stool testing. If undigested fats appear in the stool, it suggests that the body is struggling to absorb healthy fats, which are crucial for brain function, hormone balance, and overall energy.
Another important aspect of stool testing is its ability to measure beta-glucuronidase levels, an enzyme involved in detoxification. High levels can indicate an increased risk of toxin reabsorption, which can contribute to inflammation, hormone imbalances, and mood disturbances.
By identifying specific digestive issues through stool testing, personalised treatment strategies can be developed to restore gut health, improve nutrient absorption, and support both physical and mental well-being.
struggling to gain weight despite eating well, or if you experience anxiety and low mood along with digestive issues, it’s worth exploring whether your body is properly absorbing the nutrients it needs. Stool testing can be a powerful tool in identifying underlying digestive imbalances and guiding a personalised approach to restoring gut health.
Supporting digestion is often the missing link for gaining weight, good mental health, for optimal energy levels, and overall well-being.
Would you like a bespoke nutritional programme to help you restore gut health and improve nutrient absorption? Let’s work together to get to the root of the issue and create a plan that works for you.
