When you reduce carbohydrate intake to a level that does not meet your body’s needs, the levels of several hormones change in an attempt to keep you functioning. Some of these changes may be beneficial in the short term, but over time they can negatively affect energy, mood, appetite, and blood sugar levels.
اضافة اعلان
1. Low Carbohydrate Intake May Increase Cortisol Levels
Carbohydrates signal a sense of safety—feelings of fullness and satisfaction after eating—and provide energy. When intake is reduced, the body often increases cortisol production to release stored glucose. This is part of the body’s natural stress response, but chronically elevated cortisol levels can leave you feeling overly stressed, exhausted, or hungrier than usual.
If carbohydrates remain consistently low, your body may continue producing more cortisol to help regulate blood sugar and meet energy demands.
These changes can affect how you feel day to day. Common signs include:
Increased stress levels without clear emotional triggers
Severe mid-day fatigue or feeling wired but tired at night
Strong food cravings, especially for sugar or quick energy sources
2. Slower Thyroid Hormone Activity
Healthy glucose metabolism and balanced carbohydrate intake are essential for converting thyroid hormone T4 into its active form, T3—hormones that regulate metabolism, energy use, growth, and development. When carbohydrates are very low, this conversion may slow, potentially affecting metabolism, body temperature regulation, and overall energy levels.
Research has shown that low-carbohydrate diets can reduce T3 levels regardless of calorie intake.
For many people, this shows up as subtle but noticeable changes:
Feeling colder than usual
Fatigue
Weight plateau despite continued effort
3. New Patterns of Insulin and Glucagon Fluctuations
When carbohydrate intake drops significantly, levels of insulin and glucagon—the hormones that regulate glucose—shift rapidly to maintain stable blood sugar. This can make energy levels feel less steady.
Insulin levels naturally decline on low-carbohydrate diets due to reduced glucose intake. At the same time, glucagon levels rise to help maintain blood sugar by releasing stored glycogen and producing new glucose in the liver.
You may notice symptoms such as:
Low energy, especially during exercise
Shakiness, dizziness, or nervousness between meals
Increased hunger when meals are delayed
4. Leptin Sensitivity May Improve
When carbohydrate intake decreases, leptin levels (the satiety hormone) often decline—but this does not always lead to increased hunger. As the body adapts over time to consistently lower carbohydrate intake, the hormones that regulate appetite and fullness adjust.
Many people who follow long-term low-carbohydrate or ketogenic diets report improved leptin sensitivity, meaning the brain becomes better at recognizing fullness even with lower circulating leptin levels.
At the same time, ghrelin (the hunger hormone) often remains stable or decreases, while other satiety hormones such as cholecystokinin (CCK) may increase. This makes it easier to feel full after meals.
These appetite-related changes may appear as:
Feeling full more quickly during meals
Reduced cravings between meals
A more stable and predictable appetite
5. Disruption of Reproductive Hormones
For some women, consistently low carbohydrate intake may signal that total energy intake is insufficient to optimally support reproductive function.
This can reduce the brain’s release of gonadotropin-releasing hormone (GnRH), which in turn lowers luteinizing hormone (LH) and follicle-stimulating hormone (FSH)—both essential for ovulation and regular menstrual cycles.
This pattern is common in states of low energy availability and is associated with functional hypothalamic amenorrhea, a condition in which the brain’s control center suppresses reproductive signaling due to stress, leading to missed periods.
Lower leptin levels may also contribute. Leptin helps the brain assess whether the body has enough stored energy to support reproduction, and research suggests a certain level of leptin is necessary to maintain regular menstrual cycles.
When leptin drops due to low carbohydrate intake or insufficient energy—even if total calories seem adequate—menstrual cycles may become irregular.
Signs may include:
Irregular or missed menstrual periods
Increased premenstrual symptoms
Lower energy during the second (luteal) phase of the menstrual cycle
6. Reduced Serotonin Levels, Affecting Mood
Carbohydrates play a direct role in helping tryptophan (an amino acid) enter the brain, where it is converted into serotonin—a neurotransmitter that helps regulate many brain and body functions.
Research indicates that carbohydrate intake influences serotonin pathways and satiety signaling. When carbohydrates are reduced, serotonin production may decline, potentially affecting mood, appetite, sleep, and emotional regulation.
Many people notice this effect in everyday life.
Asharq Al-Awsat
