Diets 101: Benefits and Cautions of Keto, Paleo, and Intermittent Fasting

Senior Cardiologist Dr Ramasami Nandakumar shares with us more about these diets for weight loss

If you’ve ever thought about dieting, then you’ve probably come across at least one of these diets. These diets claim to help you lose weight as well as have certain health benefits, but do they really? We spoke to Senior Cardiologist Dr Ramasami Nandakumar to find out more.

1. Ketogenic Diet

The ketogenic diet is high in fat and extremely low in carbs. By limiting your carbohydrate intake to less than 50 grams a day, your body enters a ketosis state, in which it starts burning fat for energy rather than glucose. Suggested foods for this diet include dairy, eggs, meat, poultry, seafood, vegetables and nuts.

What is your take on the ketogenic diet for weight loss?

Dr Ramasami Nandakumar: Ketogenic diets were used as an effective treatment for epilepsy in children in the 1920s. 50 years later, interest developed in the use of keto diets for weight loss. Studies show that weight loss is faster in comparison with other diets1,2. This could be due to the increased feeling of fullness from proteins, appetite suppression from ketone bodies, and increased breakdown of fats and reduced fat production.

Any caution before starting the ketogenic diet?

Dr Ramasami Nandakumar: For those with kidney disease or diabetes, it is advisable to seek physician advice and work with an experienced dietician before embarking on a very low carbohydrate diet.

2. Paleolithic Diet

The Paleo Diet or caveman diet is high in fats, moderate in proteins, and low in carbs. According to this diet, what wasn’t consumed during the Palaeolithic Era is generally bad for your body because our genetics haven’t evolved that much from our ancient ancestors.

This diet encourages a gluten-free meals and eliminates all cereal grains, wheat, barley, rye, legumes, vegetable oils, hydrogenated oils, partly-hydrogenated oils, dairy products, sugar, and processed foods in general.

What are the advantages of the paleo diet?

Dr Ramasami Nandakumar: The Paleo diet offers an increased feeling of fullness, improvements in body weight, waist circumference, blood pressure and lipid profiles. Some studies have shown the paleolithic diet to be of benefit in management of various metabolic disorders including in patients with diabetes or other markers of glycemic control.

What are the concerns with the paleo diet?

Dr Ramasami Nandakumar: Studies did not show a difference in glucose and insulin levels in comparison with a reference meal3,4. Calcium deficiency also remains a significant issue with the palaeolithic diet5. There are many anthropologists who would disagree with the evolutionary argument that the paleo diet is based upon.

3. Intermittent Fasting

Intermittent fasting isn’t exactly a diet, but rather an eating pattern where you schedule your meals. Your body is in the fed state when it is digesting and absorbing food, which typically lasts 3-5 hours. This is when your insulin levels are high and it is hard for the body to burn fat. The post–absorptive state lasts 8-12 hours after your last meal, which is when you enter the fasted state. It is much easier for you body to burn fat in the fasted state because your insulin levels are low.

What are the advantages of intermittent fasting?

Dr Ramasami Nandakumar: Results from the limited number of intervention trials of modified fasting regimens suggest that these eating patterns result in weight loss, with modest and mixed effects on glucoregulatory markers, lipids, and inflammatory markers6,7,8.

Modified fasting appears to result in weight loss and metabolic health but the optimal pattern is not known. Reduced nighttime eating or prolonged nightly fasting appears to confer benefits on human health though only suggestive data are thus far available and further research is needed9.

What are the concerns with intermittent fasting?

Dr Ramasami Nandakumar: Alternate day fasting results in weight loss and reduction in glucose and insulin levels but is not well tolerated as fasting days are associated with intense hunger. It may lead to an increased fixation on food for some.
Intermittent fasting may not be appropriate for those with conditions that need food at regular intervals or use medications requiring food intake, those in active growing stage such as adolescents and pregnant or breastfeeding women. It also may not be appropriate for those with eating disorders10.

About Dr Ramasami Nandakumar

Dr Ramasami Nandakumar is a Senior Interventional Cardiologist with Cardiac Centre International that is part of the Singapore Medical Group with a network of more than 27 clinics. He consults at Mount Elizabeth Hospital, Gleneagles Hospital and Mount Alvernia Hospital, and is also a Visiting Senior Consultant at Ng Teng Fong Hospital and National University Hospital. You can reach Dr Kumar on +65 82616483 (WhatsApp) or via his online platform, Heart2Heart.



Foster GD, Wyatt HR, Hill JO, et al. A randomized trial of a low-carbohydrate diet for obesity. N Engl J Med. 2003;348:2082-90.
Samaha FF, Iqbal N, Seshadri P, et al. A low-carbohydrate as compared with a low-fat diet in severe obesity. N Engl J Med. 2003;348:2074-81.
Bligh HF, Godsland IF, Frost G, et al. Plant rich mixed meals based on Palaeolithic diet principles have a dramatic impact on incretin, peptide YY and satiety response, but show little effect on glucose and insulin homeostasis: An acute-effects randomised study. Br J Nutr 2015;113: 574–84.
Mellberg C, Sandberg S, Ryberg M, et al. Longterm effects of a Palaeolithic-type diet in obese postmenopausal women: A 2-year randomized trial. Eur J Clin Nutr 2014;68:350–57.
Osterdahl M, Kocturk T, Koochek A, Wandell PE. Effects of a short-term intervention with a paleolithic diet in healthy volunteers. Eur J Clin Nutr 2008;62:682–85.
Barnosky AR, Hoddy KK, Unterman TG, Varady KA. Intermittent fasting vs daily calorie restriction for type 2 diabetes prevention: a review of human findings. Transl Res. 2014;164:302–11.
Varady KA, Roohk DJ, Loe YC, McEvoy-Hein BK, Hellerstein MK. Effects of modified alternate-day fasting regimens on adipocyte size, triglyceride metabolism, and plasma adiponectin levels in mice. J Lipid Res. 2007;48:2212–9.
Cnop M, Havel PJ, Utzschneider KM, Carr DB, Sinha MK, Boyko EJ, Retzlaff BM, Knopp RH, Brunzell JD, Kahn SE. Relationship of adiponectin to body fat distribution, insulin sensitivity and plasma lipoproteins: evidence for independent roles of age and sex. Diabetologia. 2003;46:459–69.
Metabolic Effects of Intermittent Fasting, Ruth E. Patterson1,2 and Dorothy D. Sears1,2,3Annu. Rev. Nutr. 2017. 37:371–93
10 Diet Review: Intermittent Fasting for Weight Loss | The Nutrition Source | Harvard T.H. Chan School of Public Health

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