When should you eat? New research reveals the best timing for fasting
A major review suggests that time-restricted eating may support metabolic health — and eating earlier could offer an additional advantage.[1]
Time-restricted eating ( TRE TRE ) is a form of intermittent fasting intermittent fasting that limits daily eating to a consistent window. Instead of prescribing particular foods or counting every calorie, it focuses primarily on when you eat.
When is the best time to start your fast?
New research reveals what meal timing could mean for your fasting results.
But does the timing of that window matter? Is an eight-hour window better than a longer one? And do you need to stop eating early in the day to see results?
A new systematic review and network meta-analysis[1] brings together the available randomized trial evidence to explore these questions.
What did the researchers study?
The review included 41 randomized controlled trials involving 2,287 participants. Each trial tested time-restricted eating for longer than one month and measured outcomes related to metabolic health.
The researchers grouped eating schedules in two ways.
First, they looked at when participants finished eating:
- early TRE: Last meal before 5 PM
- midday TRE: Last meal between 5 and 7 PM
- late TRE: Last meal after 7 PM
- self-selected TRE: Participants chose their own timing
They also compared different daily eating-window durations:
- shorter than eight hours
- exactly eight hours
- longer than eight hours
This allowed the researchers to evaluate both the overall effects of time-restricted eating and whether a particular schedule appeared more effective.
The main finding: time-restricted eating improved several health markers
Compared with usual eating patterns, time-restricted eating was associated with improvements in:
- body weight
- body mass index (BMI)
- fat mass
- waist circumference
- systolic blood pressure
- fasting blood glucose
- fasting insulin
- triglycerides
These findings don’t mean TRE is a cure-all or that everyone will experience the same results. They do, however, add to the evidence that a consistent daily eating window eating window can be a useful tool for weight management and metabolic health.
Most of the included studies were considered to have a low risk of bias, while around 60% of the evidence assessed through the network analysis was rated as moderate to high certainty.
Earlier eating windows showed an advantage
The clearest comparison involved early time-restricted eating (last meal before 5 PM) versus late time-restricted eating (last meal after 7 PM).
Across trials lasting 4–48 weeks (about eight weeks on average), early TRE led to 2.5 lbs (1.15 kg) more weight loss than late TRE. It also led to a greater reduction in fasting insulin.
The researchers rated the certainty of the evidence for these two findings as high.
Early TRE also tended to rank more favorably across other body-composition and blood-sugar measures.
One possible explanation for this is that our metabolism follows a circadian rhythm. The body generally handles glucose and insulin more efficiently earlier in the day, while eating close to bedtime may be less aligned with its internal clock.[2,3]
Still, the average difference in weight was modest. An earlier window may provide an advantage, but it isn’t the only factor that matters — and it won’t be practical for everyone.
Is a shorter eating window always better?
Not according to this review.
The results for eating-window duration were inconsistent. Windows shorter than eight hours didn’t reliably outperform eight-hour or longer windows across metabolic outcomes.
That’s an important practical takeaway. A highly restrictive schedule isn’t automatically the most effective one, and extending a fast as long as possible may add difficulty without guaranteeing a greater benefit.
The best schedule is often one that creates a meaningful overnight fasting period while still allowing you to eat enough nourishing food and follow the routine consistently.
What does this mean for your fasting routine?
The evidence points to several practical principles.
1. Consider moving your eating window earlier
If your lifestyle allows it, finishing dinner a little earlier may be worth trying. You don’t necessarily need to stop eating before 5 PM. Even a gradual shift away from late-night meals and snacks can make your routine more aligned with your natural sleep-wake cycle.
2. Don’t chase the shortest possible window
The review didn’t identify one clearly superior eating-window length. Rather than jumping straight into an aggressive schedule, begin with something manageable — such as 12:12 or 14:10 — and adjust based on your wellbeing, goals, and daily routine.
3. Consistency matters more than perfection
A schedule that looks ideal on paper won’t help much if it’s impossible to maintain. Work, family meals, exercise, sleep, medication, and hunger patterns all affect which routine is realistic. A slightly later or longer eating window that you can follow consistently may serve you better than an “optimal” plan that creates stress or repeatedly breaks down.
4. Food quality still counts
Time-restricted eating determines when you eat, not whether your meals meet your nutritional needs. Balanced meals containing protein, fiber-rich carbohydrates, healthy fats, calcium-containing foods, and plenty of minimally-processed foods remain important.
How Simple can help
Research can identify useful patterns, but turning them into a routine that works in real life is often the harder part.
Simple can help you experiment with time-restricted eating while making the process feel … well, simple! You can use the Simple app to:
- choose a fasting schedule that fits your lifestyle
- track when your eating window begins and ends
- see your fasting patterns and progress
- observe how fasting affects your hunger, energy, sleep, and consistency over time
Fasting also works best as part of a broader set of sustainable habits, including good nutrition, regular movement, hydration, and sleep. Simple can help you build those habits too. You can use the app to:
- log meals, hydration, movement, and weight
- get personalized feedback on your daily nutrition
- make daily action plans with Avo™, Simple’s AI health coach
- gradually adjust your routine based on your progress and how you feel
- try fun at-home workouts across a wide range of fitness styles, including tai chi, chair yoga, wall Pilates, and more
Take our quick quiz to get your personalized plan and try Simple today!
Frequently asked questions
What’s the best intermittent fasting schedule?
There’s no single intermittent fasting schedule that works best for everyone. Beginners may find a 12:12 or 14:10 schedule easier to maintain, while more experienced fasters may prefer 16:8. The review suggests that the timing of your eating window may be more important than making it as short as possible, so choose the schedule that works for you.
Does intermittent fasting reduce belly fat?
Intermittent fasting may help reduce body fat and waist circumference as part of overall weight loss. However, it can’t specifically target fat around your stomach. Your genetics, nutrition, activity levels, sleep, stress, and overall energy intake can all influence where and how quickly you lose fat.
How long does intermittent fasting take to work?
There’s no fixed timeline for how long it takes to see results with intermittent fasting. Some people notice changes in their hunger, energy, or eating habits within the first few weeks, while changes in weight and health markers may take longer. Results will vary from person to person.
Is it better to skip breakfast or dinner when intermittent fasting?
Research suggests that an earlier eating window may offer some advantages, which could make finishing dinner earlier preferable to delaying your first meal until later in the day.[1] However, the best approach is one that fits your lifestyle, meets your nutritional needs, and feels sustainable. If you don’t know what might work for you, experiment!
What can I eat or drink during a fasting window?
Water is always a good choice. Black coffee and unsweetened tea are also commonly included because they contain very few or no calories. Foods and calorie-containing drinks generally end a fast, so these are better suited to your eating window.
Can you exercise while intermittent fasting?
Many people can exercise while following an intermittent fasting plan, but the best timing for you and how intensely you can work out will depend on your experience, energy levels, health, and fitness. If you want to try exercising while fasting, start gently, stay hydrated, and pay attention to how you feel. Test out whether it works better when you’re fasted, or when you’re fed.
Is time-restricted eating safe for everyone?
No. Time-restricted eating may not be appropriate if you’re pregnant or breastfeeding, have a history of an eating disorder, take glucose-lowering medication, are under 18 or over 80, or have a medical condition affected by changes to meal timing. Speak with a qualified healthcare professional before beginning a fasting routine if you’re unsure whether it’s suitable for you. And if fasting leaves you dizzy, weak, or unwell, stop and seek advice from a qualified healthcare professional.
