Does intermittent fasting work better than a normal diet for weight loss?

Not clearly. Evidence to date suggests it helps some people mainly by reducing overall calories, but head-to-head studies show no significant advantage over standard balanced calorie reduction. The best approach is the one you can sustain.

Is intermittent fasting safe if I have diabetes?

Not without medical advice. Fasting can cause dangerous low blood sugar, especially on insulin or certain tablets. Speak to your diabetes healthcare team first so medication can be adjusted; if you have hypo symptoms, break the fast and treat it immediately — a severe hypo is an emergency (995).

Can I eat whatever I want during my eating window?

No. IF is about timing, not a free pass. Food quality still matters — build balanced meals of vegetables, wholegrains, protein and healthier fats, and do not overeat to “make up” for the fast.

Who should avoid intermittent fasting?

Pregnant or breastfeeding women, children and teens, frail older adults, anyone underweight or with a history of an eating disorder, people on medicines that must be taken with food, and people with diabetes without medical supervision.

Is Ramadan fasting the same as intermittent fasting?

No — Ramadan is religious fasting, distinct from IF done for weight or metabolic reasons. If you have a health condition, are pregnant, or take regular medication, get medical advice before fasting; some people, such as those on insulin, may be medically exempt.

Intermittent Fasting in Singapore: Does It Work?

Written & reviewed by the BestDoctors.sg editorial team · Last updated 25 Aug 2026 · General information, not medical advice

Intermittent fasting (IF) means cycling between periods of eating and voluntarily not eating — it is an eating pattern, not a specific food plan. Common approaches include time-restricted eating (such as 16:8), the 5:2 pattern, and alternate-day fasting. The honest summary of the evidence is that IF may help some people with weight and metabolic markers, largely by reducing overall calories, but it is not clearly superior to other balanced, calorie-reduced approaches. It is one option, not a magic bullet — and several groups should not fast without medical advice.

Want practical, personalised help with food and nutrition?

Message our care team on WhatsApp. Tell us what’s going on and we’ll help you find the right dietitian — free, with no obligation.

Chat with our care team on WhatsApp

Not sure who to see? Find the right specialist →

In a medical emergency, or for severe or sudden symptoms such as breathing difficulty, chest pain, fainting or stroke signs, call 995 immediately.

People with diabetes (especially on insulin or medicines that cause low blood sugar), pregnant or breastfeeding women, children, frail older adults, anyone with an eating-disorder history, and those on medicines that must be taken with food should not fast without medical advice. Severe low blood sugar is a 995 emergency.

What it is

Intermittent fasting focuses on when you eat rather than what you eat. Time-restricted eating confines all food to a set daily window, such as eight hours, and fasts the rest; the 5:2 pattern involves eating normally on five days and sharply reducing calories on two non-consecutive days; and alternate-day fasting alternates normal-eating days with very-low-calorie or fasting days. These are timing strategies layered on top of a diet, and their healthiness still depends on the quality of the food eaten.

What the evidence shows

IF may help some people lose weight and improve some metabolic markers, largely because it tends to reduce overall calorie intake rather than through any unique metabolic effect. Evidence reviews such as Harvard’s note that head-to-head trials generally show no significant difference in weight loss or body composition compared with standard continuous calorie restriction, and a year-long trial found no significant differences in weight, blood pressure, cholesterol or glucose between the two. Long-term evidence is still developing, and much of the strongest metabolic data comes from animal studies that do not always translate to humans.

What the evidence does not show

It is important to be clear about the limits. IF is not shown to be superior to other sensible, calorie-reduced diets; it does not “detox” the body; and it is not a magic bullet. The best diet for weight and metabolic health is the one a person can actually sustain, and for some people the structure of a fasting window is helpful, while for others regular balanced meals work better. Framing IF as one tool among several, rather than the answer, keeps expectations realistic.

How to try it safely

If IF is suitable for you, check with a doctor or dietitian first if you have any health condition or take regular medication, then start gently — for example a modest overnight-extended window rather than an aggressive fast. Stay well hydrated, and be cautious with exercise, driving or operating machinery if you feel light-headed. Crucially, food quality in the eating window is central: IF is not a licence to eat anything, so build meals on the My Healthy Plate model of vegetables, wholegrains, lean or plant proteins and healthier fats, and avoid “rewarding” the fast with fried or sugary binges. Stop and reassess if it causes persistent low energy, poor concentration or any drift toward disordered eating.

Side effects

Common side effects include hunger, irritability, low energy, poor concentration and headaches, and sometimes constipation or poor sleep, particularly when starting. There is also a risk of overeating or rebound when food is reintroduced, which can undo the point of the fast. These effects often settle as the body adjusts, but if they persist or interfere with daily life, fasting may not be the right approach for you.

Who should not fast

Several groups should not fast without professional advice. People with diabetes — especially those on insulin or medicines that can cause low blood sugar — face a real risk of dangerous hypoglycaemia, and Diabetes UK advises speaking to the healthcare team first so timing and medicines can be adjusted; know the symptoms of a hypo (shakiness, sweating, confusion), break the fast and treat it immediately, and treat a severe hypo or collapse as a 995 emergency. Pregnant and breastfeeding women, children and teenagers, frail older adults, anyone with a history of an eating disorder, people who are underweight, and those on medicines that must be taken with food should also avoid fasting without medical guidance.

Fasting in Singapore, including Ramadan

For anyone fasting, anchor healthy eating to HPB’s My Healthy Plate during eating windows, and consider seeing an accredited dietitian before a major dietary change, especially with a health condition. Ramadan fasting is culturally very relevant in Singapore but is religious fasting, distinct from IF done for weight or health; people with diabetes or other conditions, or on medication, should seek advice before fasting, and some — for instance those on insulin — may be medically exempt. Whether fasting for health or faith, breaking the fast with balanced meals rather than heavy fried or sugary spreads is the healthier approach, and drinking enough water outside fasting hours helps prevent headaches and fatigue. An accredited dietitian can help you decide whether a fasting pattern fits your routine and health, or whether a simpler approach of balanced, portion-controlled meals would serve you better.

Related nutrition & healthy-eating topics

Sources

Harvard T.H. Chan School of Public Health — Intermittent fasting: nutritionsource.hsph.harvard.edu
Diabetes UK — Fasting and diabetes: diabetes.org.uk
HealthHub — Nutrition Hub: healthhub.sg

General information only. This guide is general nutrition information and is not personalised dietary or medical advice. Individual needs vary with age, health conditions, medicines and pregnancy, so speak to a doctor or an accredited dietitian before making major dietary changes — especially if you have diabetes, kidney disease, are pregnant, or take medicines that interact with food. Seek medical advice for unexplained weight loss, difficulty swallowing, or a sudden change in appetite, and call 995 for a medical emergency such as choking or a severe allergic reaction (swelling of the face or throat, difficulty breathing).