Hydration, Nutrition, and Metabolism: Experts Reveal the Science Behind Your Energy
Some individuals notice greater mental clarity and a sense of calm while fasting during Ramadan, whereas others experience headaches, fatigue, and midday brain fog. Doctors told Gulf News that these differences often depend on how adaptable and resilient a person’s metabolism is.
The Metabolic Switch
Dr. Niyas Khalid, Specialist in Internal Medicine at Burjeel Hospital, Abu Dhabi, explained that fasting sets off a precisely coordinated metabolic shift.
“In the fed state, the body primarily relies on glucose, regulated by insulin. Once fasting begins, insulin levels drop, glycogen stores are gradually tapped, and the body initiates a metabolic switch,” he said.
As fat is broken down, the liver produces ketone bodies, which serve as an alternative fuel for the brain.
“In people with resilient metabolisms, this transition occurs smoothly. The mitochondria—the energy-producing structures in our cells—efficiently switch to burning fat-derived substrates, leading to steady energy levels and sharper mental clarity,” Dr. Khalid explained.
When the Shift Feels Harder
Not everyone transitions smoothly to fasting.
“If a person has underlying insulin resistance, high blood sugar fluctuations, disrupted sleep, micronutrient deficiencies, or elevated stress hormones, the metabolic shift can feel destabilising,” Dr. Niyas Khalid explained. Rather than efficiently burning fat, the body may trigger exaggerated stress responses or fluctuating glucose levels, resulting in fatigue, headaches, and irritability.
The Role of Diet, Sleep, and Hydration
Consuming meals high in sugar or refined carbohydrates at iftar and suhoor can cause sharp blood sugar swings, leading to energy crashes, Dr. Fathima Anthony explained.
Adequate sleep and proper hydration also play a key role in how the body handles fasting. Irregular sleep, early suhoor wake-ups, and insufficient fluid intake can amplify fatigue, headaches, and brain fog.
Dr. Fathima Anthony, Family Medicine Specialist at NMC Specialty Hospital, Al Nahda, Dubai, emphasized that hydration and sleep are equally crucial.
“Fatigue can result from dehydration, lower calorie intake, caffeine withdrawal, or disrupted sleep,” she noted.
“Eating meals rich in sugar or refined carbohydrates at iftar and suhoor can cause blood sugar swings, which may lead to sudden energy crashes.”
Underlying Conditions
Existing medical conditions can strongly impact how a person feels during fasting.
“Diabetes, anaemia, and hypothyroidism can greatly affect energy levels,” Dr. Fathima explained. “People with chronic conditions should consult their physician before fasting and make sure they maintain proper nutrition, stay hydrated, and get enough rest.”
When Suhoor Sets the Tone
Doctors emphasise that what you eat at suhoor can shape how steady your energy remains throughout the day.
Dr. Niyas Khalid noted that a suhoor heavy in refined carbs or sugars causes a rapid spike in blood glucose and insulin, often leading to a morning crash and midday fatigue. In contrast, a balanced meal with protein, fibre, and healthy fats “slows glucose absorption” and provides a more gradual, sustained release of energy.
Hydration between iftar and suhoor is equally important— even mild fluid deficits can reduce concentration and worsen fatigue.
Iftar Structure Matters
“Iftar is another crucial part of fasting,” Dr. Niyas Khalid explained. He advised breaking the fast gently before moving on to a balanced meal, allowing the body to “recalibrate” without being overwhelmed. Consuming excessively sugary or heavily processed foods, he warned, can lead to reactive lethargy later in the evening and interfere with sleep.
How to Sustain Energy
Doctors recommend the following strategies to maintain steady energy levels throughout Ramadan:
How to Sustain Energy
- Prioritise protein and fibre at suhoor – Supports steady blood sugar and prolonged energy.
- Limit refined sugars at iftar – Helps prevent energy crashes and evening lethargy.
- Stay hydrated between sunset and dawn – Even mild dehydration can impair concentration and increase fatigue.
- Maintain consistent sleep patterns – Adequate rest helps the body adjust to fasting and boosts overall energy.
Avoid extreme overeating or under-eating – “Fasting shouldn’t be confused with severe calorie restriction,” Dr. Niyas Khalid explained. When approached with balance, fasting gives the body periods of metabolic rest while still ensuring adequate nourishment.
