Our Bodies Were Not Designed to Eat All Day: Why We Need to Start Intermittent Fasting
TL;DR: Intermittent fasting is an eating pattern that creates defined periods without food. Research suggests that time-restricted eating can support modest improvements in body weight, fat mass and some metabolic markers. But fasting isn't magic, and longer isn't necessarily better. The real value may be in creating structure around eating and reducing unnecessary snacking.
Why Are We Eating All Day?
Think about a typical day.
Breakfast. Coffee. A mid-morning snack. Lunch. Another coffee. Something with tea. Dinner. Something sweet while watching television.
Food is now available almost everywhere, almost all the time. And our bodies haven't changed nearly as quickly as our food environment has.
The World Health Organization reports that 1 in 8 people globally were living with obesity in 2022, with adult obesity more than doubling since 1990. WHO also describes obesity as a complex, chronic condition influenced by diet, physical activity, genetics, environment and behaviour.
That doesn't mean we should blame food or blame ourselves. It does mean that creating some structure around when we eat is worth considering. That's where fasting comes in.
What Is Intermittent Fasting?
Intermittent fasting (IF) is simply an eating pattern that alternates periods of eating with periods without food.
One of the most common forms is time-restricted eating (TRE), where you consume your food within a consistent daily window.
For example:
12:12 - 12 hours fasting, 12 hours eating
14:10 - 14 hours fasting, 10 hours eating
16:8 - 16 hours fasting, 8 hours eating
You don't have to jump straight to 16:8. If you finish dinner at 8 PM and eat breakfast at 8 AM, you're already doing a 12-hour overnight fast. That may be enough to eliminate some unnecessary late-night eating.
And that's an important point: Fasting isn't a competition to see how long you can go without food.
What Happens When You Stop Eating?
When we eat, insulin rises and the body processes and stores incoming nutrients. When we stop eating, insulin generally falls and the body gradually shifts towards using stored energy.
Initially, glycogen - the body's stored form of glucose - plays an important role. As fasting continues, the body increasingly relies on stored fat and, during longer periods, ketones. This is sometimes described as a metabolic switch.
But let's be careful with the language.
Fasting doesn't "reset" your metabolism.
It doesn't magically burn away body fat.
And it certainly doesn't cancel out what you eat during your eating window.
The potential benefit is much simpler: Fasting can create structure around eating and may make it easier for some people to manage overall energy intake.
Does Intermittent Fasting Actually Work?
The research increasingly suggests that it can. A 2025 umbrella review covering 12 meta-analyses and 122 health-outcome associations found evidence that time-restricted eating was associated with weight loss, reduced fat mass and improvements in markers including fasting insulin and HbA1c, particularly in adults with overweight or obesity. The researchers also emphasised that longer-term and individualised research is still needed.
A 2026 systematic review and network meta-analysis of 41 randomised controlled trials involving 2,287 people found that time-restricted eating improved body weight, BMI, fat mass, waist circumference, systolic blood pressure, fasting glucose, fasting insulin and triglycerides compared with usual diets. Interestingly, earlier eating windows appeared more favourable than later ones, while the evidence on exactly how long the eating window should be was inconsistent.
So the evidence is encouraging. But that doesn't mean: "Fasting is better than every other diet."
It means fasting can be one useful tool for some people.
Fasting Doesn't Give You Permission To Eat Anything
This is where many fasting plans go wrong. Someone fasts for 16 hours and then thinks: "I've earned this."
And suddenly the eight-hour eating window becomes a free-for-all. Fasting doesn't work that way.
A healthy eating window still needs adequate protein, fibre, vegetables, healthy fats and nutrient-dense foods.
If you're fasting but spending your eating window on ultra-processed food, excessive calories and constant snacking, the fasting window isn't going to magically make the overall diet healthy.
Fasting is a tool. It isn't a nutritional philosophy.
What About Exercise and Muscle?
This is particularly important as we get older. The goal shouldn't simply be to weigh less. We want to preserve muscle while managing excess body fat.
Research combining time-restricted eating with exercise is encouraging. A 2024 systematic review and meta-analysis of 19 randomised controlled trials involving 568 participants found that time-restricted eating combined with exercise reduced body mass and fat mass compared with exercise plus a control diet.
That makes the combination much more interesting than fasting alone.
Strength training + adequate protein + sensible nutrition + movement + sleep + an appropriate eating window is a far more useful framework.
What About Women and Hormones?
This is where we need to be particularly careful. There are plenty of claims online that fasting "balances women's hormones" or that women should follow very specific fasting schedules according to their menstrual cycle.
Some of these ideas are interesting. But the evidence isn't strong enough to treat them as universal rules.
A 2024 review examining intermittent fasting and female reproductive function concluded that the area is still evolving and that drawing definitive conclusions remains difficult. Some studies suggest potential benefits in women with overweight or PCOS, while other research raises questions about reproductive effects under certain fasting conditions.
So I wouldn't tell every woman: "You should fast."
Nor would I tell every woman: "You should never fast."
The right question is: Does this eating pattern provide enough nutrition and energy for your particular body, lifestyle and health needs?
That becomes even more important during pregnancy, breastfeeding, periods of intense training or when dealing with medical conditions.
What About PCOS and Fertility?
PCOS is one area where fasting has attracted considerable interest. Some early research suggests that time-restricted eating may help improve metabolic and reproductive markers in women with PCOS. But the evidence base is still small.
That means we should not turn: "There is promising research" into "Fasting treats PCOS."
The same principle applies to fertility. There is good evidence that excess body weight and metabolic dysfunction can affect reproductive health. But that doesn't mean fasting itself is a fertility treatment.
If fasting helps an individual improve their overall metabolic health and body composition, there may be indirect benefits. That's very different from claiming that fasting directly improves fertility.
Who Should Be Careful With Fasting?
Fasting isn't appropriate for everyone. Anyone who is pregnant or breastfeeding, underweight, has a history of an eating disorder, has diabetes or recurrent hypoglycaemia, takes medication affected by food intake or has a significant medical condition should speak with an appropriate healthcare professional before changing their eating pattern.
And there is another important rule: If fasting consistently makes you exhausted, dizzy, excessively hungry or causes you to overeat later, the strategy may not be working for you. There's no prize for forcing yourself through it.
How Should You Start?
You don't need to begin with 16:8.
Start with something boring like 12:12.
Finish dinner at 8 PM.
Have breakfast at 8 AM.
Then see how you feel.
If that is comfortable, you could experiment with 14:10.
You may eventually find that 16:8 works for you.
Or you may discover that 12:12 is perfectly adequate.
The goal is not to find the most extreme fasting protocol. The goal is to find an eating pattern you can actually live with.
Fasting Is One Part of Wellness
This is perhaps the most important point.
Fasting cannot compensate for poor sleep.
It cannot replace exercise.
It cannot fix a poor-quality diet.
And it certainly cannot eliminate chronic stress.
Wellness is a system. Nutrition, movement, strength, sleep, stress management and recovery all interact. That is why our broader WellnessFusion content looks beyond food alone - especially for founders. Meditation, Breathwork and tracking data using Wearables is a natural next step.
So, Should You Start Fasting?
Maybe. But don't start because someone on Instagram told you that fasting will "reset your hormones", "detox your body" or magically burn fat.
Start because you want to experiment with creating more structure around eating.
Try 12 hours first.
Eat well during your eating window.
Keep exercising.
Get enough protein.
Sleep properly.
Pay attention to how your body responds.
And if it works for you, great.
If it doesn't, there are plenty of other healthy ways to structure your nutrition.
Because perhaps the more useful question isn't: "How long can I go without eating?"
It's: "Do I really need to be eating all day?"
Frequently Asked Questions
Is 16:8 fasting better than 12:12?
Not necessarily. Research suggests time-restricted eating can be beneficial, but the evidence does not show that everyone needs an eight-hour eating window. The ideal approach depends on the individual.
Can intermittent fasting help with weight loss?
Yes, research suggests it can support modest reductions in body weight and fat mass, particularly when combined with an appropriate diet and lifestyle.
Does fasting cause muscle loss?
It doesn't necessarily. When combined with exercise, research suggests time-restricted eating can reduce body fat while supporting preservation of lean mass.
Is fasting safe for women?
It can be for some women, but individual circumstances matter. Evidence around female reproductive health is still developing, so pregnancy, breastfeeding, eating disorders, inadequate energy intake and certain medical conditions require particular caution.
Can fasting cure PCOS or improve fertility?
No. Current research is promising in some areas but not strong enough to describe fasting as a treatment for PCOS or infertility.
What is the easiest way to start?
Start with a 12-hour overnight fast. If that feels comfortable, you can decide whether a longer eating window is appropriate for you.
About Arpita Bose & WellnessFusion
Arpita Bose is the wellness entrepreneur behind WellnessFusion, bringing together nutrition, movement, yoga and sustainable lifestyle practices. Her approach is simple: wellness should not be another extreme project. It should be something you can sustain while living a full life.
This article combines practical wellness experience with published research. It is intended for educational purposes and should not be treated as medical advice.
