People fast today for a wide range of reasons, from religious observance to weight management to mental clarity. About 13 percent of American adults experimented with intermittent fasting in 2024, and millions more worldwide participate in religious fasts tied to specific dates on the calendar. Whether you’re wondering about a specific observance happening right now or trying to understand the broader trend, here’s what’s driving so many people to voluntarily skip meals.
Religious Fasts Throughout the Year
If you noticed coworkers, friends, or family members fasting on a particular day, there’s a good chance it’s tied to a religious observance. Several major traditions build fasting into their calendars as a spiritual discipline.
Ramadan is the most widely practiced fast globally. During the ninth month of the Islamic calendar (February 19 through March 20 in 2026), Muslims abstain from food and drink from sunrise to sunset for an entire month. It’s a period of prayer, reflection, and community, observed by roughly 1.8 billion Muslims worldwide.
Lent begins on Ash Wednesday each year and lasts 40 days leading up to Easter. Some Christians fast completely on Ash Wednesday and Good Friday, while others give up specific foods or habits for the full period. Practices vary widely across denominations.
Yom Kippur, the Jewish Day of Atonement, involves a roughly 25-hour fast from sundown to sundown. It’s considered the holiest day of the Jewish year, devoted entirely to prayer and repentance. A special meal is eaten before sundown to begin the fast.
Hinduism, Buddhism, and other traditions also include regular fasting days tied to lunar cycles or specific festivals. On any given day of the year, there’s likely a religious community somewhere observing a fast.
The Intermittent Fasting Trend
Beyond religion, millions of people fast as a health practice. Intermittent fasting has become one of the most popular dietary approaches in the world, with proponents praising it for being easier to follow than traditional calorie-counting diets. Instead of tracking every meal, you simply restrict when you eat. The most common patterns involve eating within a 6 to 8 hour window each day, or fasting for a full 24 hours once or twice per week.
The appeal is simplicity. There are no special foods to buy, no points to calculate, no meals to prep. You just stop eating at a certain time and start again later. For many people, that binary structure feels more sustainable than the constant decision-making of conventional diets.
What Fasting Does to Your Body
When you stop eating for an extended period, your body shifts from burning glucose to burning stored fat for energy. The liver converts fat into molecules called ketone bodies, which your cells, including brain cells, can use as fuel. This metabolic switch is the foundation of most claimed fasting benefits.
A large meta-analysis of clinical trials found that intermittent fasting reduces fasting blood glucose, lowers circulating insulin levels by an average of about 13 mU/L, and modestly improves insulin resistance scores. These changes matter most for people with early signs of blood sugar problems. For healthy individuals, the improvements are smaller and less clinically meaningful.
One headline finding: a clinical trial published in the New England Journal of Medicine compared time-restricted eating (a form of intermittent fasting) with standard calorie restriction and found that both approaches produced similar reductions in body fat and visceral fat. In other words, fasting works for weight loss, but it doesn’t appear to work better than simply eating less. The advantage is psychological, not metabolic. If fasting makes it easier for you to eat fewer calories overall, it’s a useful tool.
Brain Effects and Mental Clarity
Many people who fast regularly report sharper thinking and improved mood, and there’s some biological basis for this. When your liver produces ketone bodies during a fast, those molecules travel to the brain and trigger the production of a protein that supports the growth and maintenance of nerve cells. In animal studies, this protein promotes the formation of new connections between neurons, strengthens cellular defenses against stress, and may even support the growth of new brain cells in memory-related areas.
One mouse study found that even a 9-hour fast was enough to increase levels of this protective protein and produce measurable antidepressant effects. Human research is less conclusive, though. A study comparing younger and older healthy adults on a periodic fasting diet found no clear differences in memory improvement between the two groups. The brain benefits of fasting are plausible and supported by animal research, but the human evidence is still catching up.
Fasting for Longevity
Some of the most striking fasting research involves biological aging. A clinical trial tested a “fasting-mimicking diet,” a 5-day protocol of very low calorie, plant-based eating done once a month for three months. After three cycles, participants showed a median decrease of 2.5 years in biological age, measured by a validated tool that predicts disease risk and mortality. A second trial replicated this, finding a 2.7-year decrease. Control groups who ate normally showed no change.
Participants also showed improved immune system markers. Specifically, the ratio of two types of white blood cells shifted toward a younger profile, reversing part of the age-related decline in immune function. These changes held even after participants returned to their normal diets, and they occurred independent of weight loss. In mice, the same periodic fasting protocol reduced inflammation, promoted tissue regeneration across multiple organ systems, and extended lifespan.
Dopamine Fasting and Digital Detox
Not all modern fasting involves food. “Dopamine fasting” has gained traction in productivity and wellness circles as a way to reset the brain’s reward system. The practice involves temporarily abstaining from stimulating activities like social media, video games, streaming, and sometimes even conversation, with the goal of reducing dependence on instant gratification.
Proponents say that after a period of deliberate understimulation, everyday activities feel more rewarding again. The idea is that constant exposure to high-stimulation content dulls your ability to enjoy simpler things, and taking a break recalibrates your baseline. The name is somewhat misleading (you can’t actually deplete dopamine by scrolling your phone), but the underlying concept of giving your attention and reward circuits a rest resonates with many people who feel overwhelmed by digital life.
Who Should Be Cautious
Fasting is not appropriate for everyone. People with diabetes face real risks from extended periods without food, including dangerous drops in blood sugar, especially if they take insulin or certain medications. Anyone with a history of disordered eating may find that the rigid rules around fasting trigger or worsen unhealthy patterns. Pregnant or breastfeeding women, children, and people who are underweight should avoid fasting protocols designed for weight loss.
Even for healthy adults, the first few days of a new fasting routine commonly bring headaches, irritability, difficulty concentrating, and fatigue. These symptoms typically ease within a week or two as the body adapts to the new eating pattern. Starting with a shorter fasting window and gradually extending it makes the transition easier for most people.