Weight Loss Diet in Singapore: Keto vs Fasting

20 Oct

Keto, fasting or just eating less? What hundreds of trials say about weight-loss diets

20 October 2026 Weight Loss, Keto Diet, Intermittent Fasting 6-Minute Read
Information reviewed by: Dr Lye Tong Fong, MBBS (S'pore)
Last updated:

Every popular diet works for someone. The research shows why, how big the differences really are, and how to pick the one you can live with. Use the toolkit further down to find your best fit.

One rule sits under every diet

You lose fat when your body uses more energy than you eat. Keto, fasting, vegetarian and calorie counting are different ways of getting there. Think of them as routes on a map app: they all reach the same destination. The best route is the one with the fewest roadblocks for you.

That is not just a slogan. When researchers give people the same calories on different diets, the gaps mostly shrink to around 1 kg. In a 2024 trial, eating within a 10-hour window with calories held equal gave the same 12-week weight loss as normal eating times (2.3 kg vs 2.6 kg).1 The clock helped only when it led people to eat less.

How much extra weight does each diet lose, compared with a standard calorie-cut diet?

Keto: 2026 meta-analysis of trials with matched calorie targets.2 Alternate-day fasting: BMJ 2025 network meta-analysis, 99 trials, 6,582 adults.3 Higher protein: meta-analysis of 24 trials, 1,063 adults.4 Time-restricted eating: TRIM trial, Annals of Internal Medicine 2024.1 The 2 kg line is the smallest difference the BMJ authors counted as clinically important.

  • No diet clears the 2 kg line. The "winners" win by about the weight of a bag of rice.
  • In the BMJ review, only trials shorter than 24 weeks showed fasting beating normal calorie cutting. In longer trials the advantage disappeared.
  • In DIETFITS (609 adults, 12 months), healthy low-fat lost 5.3 kg and healthy low-carb 6.0 kg, a statistical tie.5

Nine diets, what the research shows, and who each one suits

Tap a diet to see how it works, what the evidence shows, who it suits and what to watch for.

Evidence bars
  • Large long-term trials
  • Good short-term trials
  • Limited or mixed

How
Half the plate vegetables and fruit, a quarter wholegrains, a quarter protein. Cut about 500 kcal a day.
Evidence
The benchmark every other diet is tested against. Matches the others over 12 months.
Suits
Hawker-centre eaters, families, anyone who dislikes strict rules.
Watch
Portion creep. Weigh or photograph meals for the first few weeks.

How
Olive or other unsaturated oils, fish, beans, nuts, vegetables, wholegrains. Less red meat and sweets.
Evidence
In DELISH (2026, 24 months) it lost the same ~4.5 kg as a commercial plan, with much better diet quality.6 The BMJ 2020 review of 14 named diets found only this one kept heart benefits at 12 months.7
Suits
High blood pressure, high cholesterol, heart risk, long-term maintenance.
Watch
Nuts and oil are calorie-dense. Measure, don't pour.

How
Carbs at roughly 10–26% of calories. Half portion of rice or noodles, swap sugary drinks, more protein and vegetables.
Evidence
A 110-trial review found each 10% cut in carbs added about 1.15 kg loss at 12 months.8
Suits
Prediabetes and type 2 diabetes, people whose hunger is driven by sweet or starchy food.
Watch
If you take insulin or certain diabetes tablets, doses may need lowering first.

How
Carbs under about 10% of calories, so the body switches to burning fat and making ketones.
Evidence
About 1.5 kg extra loss with calories matched (2026 meta-analysis).2 Beyond a year, older reviews put the edge under 1 kg.
Suits
Short, supervised phases where a faster start matters.
Watch
LDL cholesterol can rise. Not for pregnancy, kidney disease or an eating-disorder history without specialist advice. The first week's drop is mostly water.

How
Eat within an 8–10 hour window, e.g. 10am to 6pm. Fast the rest.
Evidence
About 2.8 kg more than unrestricted eating (Nutrition Reviews 2026, 30 trials)9, but no edge when calories are matched.
Suits
Late-night snackers, people who prefer a simple rule to counting.
Watch
Shift work, diabetes medicines that cause low sugar, eating-disorder history.

How
About 500–600 kcal on 2 days a week (5:2), or every other day (alternate-day).
Evidence
Alternate-day fasting was the only fasting style to beat calorie cutting (1.29 kg, BMJ 2025)3, mainly in shorter trials.
Suits
People who cope better with "on/off" days than daily restraint.
Watch
Hard to sustain for many. Avoid in pregnancy, older frail adults, and with low-sugar-risk medicines.

How
A palm-sized protein portion at every meal: eggs, tofu, fish, chicken, Greek yoghurt, beans.
Evidence
28 trials (2024): extra protein protected muscle during weight loss. Above 1.3 g/kg/day favoured muscle; below 1.0 g/kg/day raised the risk of losing it.10
Suits
Adults over 50, people on weight-loss medicine, anyone who is always hungry.
Watch
Kidney disease: check with your doctor before raising protein.

How
Build meals on beans, tofu, tempeh, wholegrains, vegetables and fruit.
Evidence
12 trials: about 2 kg more than non-vegetarian diets even without calorie targets, fading after a year.11 High fibre fills you up.
Suits
Those who already enjoy plant foods, heart and cholesterol goals.
Watch
Vitamin B12, iron and protein. Fried "mock meat" is still fried.

How
Shakes or soups replace all meals for 12–20 weeks, then food is slowly brought back.
Evidence
DiRECT: 7.6 kg loss and 36% type 2 diabetes remission at 2 years. Of those in remission at 2 years, 26% still were at 5 years.12
Suits
Recent type 2 diabetes, or when faster loss is needed before a procedure.
Watch
Needs medical monitoring and medicine changes. Weight returns without a maintenance plan.

Fasting moves when you eat. Keto changes what you burn.

Fasting, the analogy: it is like closing the kitchen at a set time. Fewer hours open usually means fewer snacks served. If the kitchen serves the same amount in fewer hours, the scale does not move faster.

Keto, the analogy: your body stores carbs like a wet sponge. Cut carbs hard and the sponge is wrung out in the first week, so 1–3 kg of water leaves fast. That early drop feels like magic, but the slower fat loss after it follows the same calorie rules as every other diet.

Which diet fits your weight plan?

Answer six quick questions, one at a time. It takes about a minute. The toolkit then ranks the diets that suit your goal, habits and health, and flags anything to discuss with your doctor first. It is a starting point for a conversation, not a prescription.

Tried but failed? Or need more efficient weight management?

Book a teleconsult

Question 1 of 6

Where are you in your weight plan?

Short videos to go with this article

My Healthy Plate explainedYouTube · HealthHub / HPB
Intermittent fasting, explained by doctorsYouTube search
Keto: benefits and risks from a dietitianYouTube search

Five things to take away

  • Calories decide fat loss. The diet decides whether you can keep the calories down.
  • Keto and alternate-day fasting win by about 1.3–1.5 kg in trials, and the edge shrinks over time.
  • Protect your muscle: protein at every meal plus strength exercise twice a week.
  • If you take diabetes medicines, are pregnant, have kidney disease or an eating-disorder history, speak with a doctor before fasting or going keto.
  • Plan the maintenance phase from day one. Most regain happens when the "diet" ends.

Not sure which route is yours?

Book a private teleconsultation. A doctor will review your health, medicines and routine, and build a diet plan you can keep. Prescription medicine is considered only where clinically appropriate, as an add-on to diet and activity. Results vary between individuals.

Book an appointment WhatsApp us

References

  1. Maruthur NM, Pilla SJ, White K, et al. Effect of isocaloric, time-restricted eating on body weight in adults with obesity: a randomized controlled trial. Ann Intern Med. 2024. PubMed 38639542. Coverage: Epocrates summary.
  2. [Ketogenic vs higher-carbohydrate diets under comparable prescribed energy: systematic review and meta-analysis of RCTs]. 2026. PubMed Central.
  3. Semnani-Azad Z, et al. Intermittent fasting strategies and cardiometabolic risk factors: systematic review and network meta-analysis of 99 randomised trials. BMJ. 2025;389:e082007. doi:10.1136/bmj-2024-082007. Coverage: PubMed Central.
  4. Wycherley TP, Moran LJ, Clifton PM, Noakes M, Brinkworth GD. Effects of energy-restricted high-protein, low-fat compared with standard-protein, low-fat diets: a meta-analysis of randomized controlled trials. Am J Clin Nutr. 2012;96(6):1281–1298. doi:10.3945/ajcn.112.044321.
  5. Gardner CD, Trepanowski JF, Del Gobbo LC, et al. Effect of low-fat vs low-carbohydrate diet on 12-month weight loss in overweight adults and the association with genotype pattern or insulin secretion: the DIETFITS randomized clinical trial. JAMA. 2018;319(7):667–679. doi:10.1001/jama.2018.0245.
  6. [DELISH randomised trial: Mediterranean-style diet vs a commercial weight-loss programme over 24 months]. JAMA Netw Open. 2026. doi:10.1001/jamanetworkopen.2026.29006.
  7. Ge L, Sadeghirad B, Ball GDC, et al. Comparison of dietary macronutrient patterns of 14 popular named dietary programmes for weight and cardiovascular risk factor reduction in adults: systematic review and network meta-analysis of randomised trials. BMJ. 2020;369:m696. doi:10.1136/bmj.m696.
  8. Soltani S, et al. Effect of carbohydrate restriction on body weight in overweight and obese adults: a systematic review and dose–response meta-analysis of 110 randomized controlled trials. Front Nutr. 2023;10:1287987. doi:10.3389/fnut.2023.1287987. Coverage: NutraIngredients.
  9. [Time-restricted eating with and without caloric restriction: meta-analysis of 30 RCTs]. Nutr Rev. 2026;84(3):463–486. PubMed 40298934.
  10. [Enhanced protein intake and lean mass during weight loss: meta-analysis of 28 RCTs]. Clin Nutr ESPEN. 2024;63:417–426. PubMed 39002131.
  11. Huang RY, Huang CC, Hu FB, Chavarro JE. Vegetarian diets and weight reduction: a meta-analysis of randomized controlled trials. J Gen Intern Med. 2016;31(1):109–116. doi:10.1007/s11606-015-3390-7. Coverage: Academy of Nutrition and Dietetics summary.
  12. Lean MEJ, Leslie WS, Barnes AC, et al. 5-year follow-up of the randomised Diabetes Remission Clinical Trial (DiRECT) of continued support for weight loss maintenance in the UK: an extension study. Lancet Diabetes Endocrinol. 2024;12(4):233–246. doi:10.1016/S2213-8587(23)00385-6. Coverage: Open-access copy (Univ. of Glasgow).

This article is general health education and does not replace advice from your own doctor.

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