A lot of people freak out about protein when following a ketogenic diet. There is an idea that eating a high, or even moderate protein diet, will result in large amounts of glucose creation from amino acids in protein (gluconeogenesis). However, this idea is unfounded and there are significant benefits from increasing your protein intake.

What is ketosis?

Ketogenic diets are those that elicit the state of ‘ketosis’. This state of ketosis refers to the production of ketone bodies, derived from fats (and some amino acids) for use as an alternative fuel in times of fasting or drastic carbohydrate restriction.

When glycogen reserves become insufficient to supply glucose to the Central Nervous System (CNS), an alternative fuel source is needed. Ketones, especially beta-hydroxybutyrate (BOHB) provide this fuel, which can be used by the brain and CNS, and by most tissue (including muscle tissue) throughout the body.

What are ketogenic diets?

The ketogenic diet itself is a form of LCHF diet that is very low in carbohydrate, low-to-high in protein and moderate-to-high in fat. It is often termed a ‘very low carbohydrate ketogenic diet’ (VLCKD). Keto diets are characterised by the expression of ketone bodies in the blood, breath, and urine. This expression of ketones is a ‘functional’ nutritional ketosis (NK) and this nutritional ketosis is usually defined by levels of ketones (specifically BOHB) in the blood of > 0.5 mmol/L.

What’s ‘Gluconeogenesis’

Gluco = sugar, neo = new, genesis = creation.

So, gluconeogenesis is the creation of glucose within the body. This is an essential process that allows the body to produce glucose from the glycerol backbone of triglycerides (fats) and most importantly, from amino acids (the building blocks of protein).

Isn’t gluconeogenesis ‘bad’ for ketosis?

Not really… and the reasons are two-fold.

• Gluconeogenesis is DEMAND, not supply-driven.

This means that the body will use the glycerol liberated from fatty acids during the breakdown of fat for fuel, to create glucose which is required in the body to fuel certain cells that can’t use fat or ketones (like red blood cells). If there is an additional requirement, the body will convert amino acids to glucose as required.

• The old-style keto diets had to be extremely low in protein to allow very high blood ketone levels to reduce the frequency and severity of seizures in children with epilepsy.

To most effectively reduce seizures, a high blood ketone level of around 2-3 mmol/L + is preferred. (1) However, nutritional ketosis for most athletes and people in the mainstream doesn’t need to be sustained at this high level and ketosis is now defined as anything above 0.5 mmol/L of BOHB. (2-6) Protein has an insulin response, and this does reduce ketosis (albeit slightly) and so, to create larger amounts of ketones in these early diets, protein was restricted. With lower demand for ketones in modern keto-diets not for epilepsy, protein can be increased without affecting the ability to get into and sustain ketosis.

So, high protein intake can result in higher insulin levels and excess amino acids from protein can be converted to glucose, but this has only a small effect on ketogenesis. Nowadays, we can also enhance ketone body production with MCT oil (allowing ketosis with higher intakes of both protein and carbohydrate) and directly ‘boost’ ketone levels with exogenous ketone supplements, when required.  

Higher-protein, low-carb diets

High-protein, low-carbohydrate diets have actually been studied quite extensively for weight-loss and improving body composition. They typically perform better than high-carbohydrate calorie-restricted diets (no surprise there) and have been used to enhance weight-loss with greater loss of body-fat, and reduced loss of muscle along with improved blood markers of health. (7-11)

Increased protein on a low-carb diet can be extremely beneficial, resulting in improved satiety (feelings of satisfaction and fullness from eating) and thermogenesis (calorie burning) when compared to equivalent amounts of either carbohydrates or fat. (12, 13) There is a higher thermic effect of feeding (TEF) (using more calories) from protein ingestion as compared to either carbohydrate or fat. (14-16) Higher protein keto-diets have been shown to increase weight loss and provide more satiety than high protein, moderate carb diets. (17)

There are significant benefits from increasing protein intake irrespective of diet, including:

• Improved bone health (18)
• In older adults, high-protein nutritional supplements are associated with lower hospital admissions and fewer health complications. (19)
• Older adults retain more lean mass and lose more fat mass during weight loss when consuming higher protein diets. (20, 21)
• Increased dietary protein has a small, beneficial effect on blood pressure, reduces triglycerides (one of the most important markers of poor cardiovascular and metabolic health), and reduces body fat stores. (22, 23)

For those dieting, or even those who are just habitual under-eaters, an increased protein intake of up to 2.5 g per kilogram of body weight is likely to help offset muscle loss, and thus improve body composition (muscle to fat ratio) resulting in a leaner you. (24)

This level of protein is around 3 x higher than the recommended daily allowance of 0.8g per kg body weight! Not only that but for ‘weekend warriors’ training for sports, or at the gym, protein taken after training might reduce soreness. (25) And in healthy adults, over the long term, protein is likely to increase lean muscle and help to improve strength and power. (26)

How to Apply This

Increasing your protein intake won’t excessively inhibit ketosis (although there might be a small reduction in ketones) not reduce your ability to lose fat or gain muscle, in contrast, there will be likely benefits to body-composition and overall health from an optimised protein intake. So, set protein at an appropriate level for your goals rather than out of fear of gluconeogenesis.

Protein recommendations (per kg of body weight per day)

• For athletic and general populations and to offset age-related muscle loss: ~ 1.4 g – 2.2 g
• When dieting: ~ 2.5 g
• When gaining muscle: ~ 2 – 2.5 g +

References

1.            Gilbert DL, Pyzik PL, Freeman JM. The ketogenic diet: seizure control correlates better with serum beta-hydroxybutyrate than with urine ketones. J Child Neurol. 2000;15(12):787-90.

2.            Guerci B, Benichou M, Floriot M, Bohme P, Fougnot S, Franck P, et al. Accuracy of an electrochemical sensor for measuring capillary blood ketones by fingerstick samples during metabolic deterioration after continuous subcutaneous insulin infusion interruption in type 1 diabetic patients. Diabetes Care. 2003;26(4):1137-41.

3.            Gibson A, Seimon R, Lee C, Ayre J, Franklin J, Markovic T, et al. Do ketogenic diets really suppress appetite? A systematic review and meta‐analysis. Obes Rev. 2015;16(1):64-76.

4.            Harvey CJdC, Schofield GM, Williden M. The use of nutritional supplements to induce ketosis and reduce symptoms associated with keto-induction: a narrative review. PeerJ. 2018;6:e4488.

5.            Harvey CJdC, Schofield GM, Williden M, McQuillan JA. The effect of medium chain triglycerides on time to nutritional ketosis and symptoms of keto-induction in healthy adults: a randomised controlled clinical trial. J Nutr Metab. 2018;2018:9.

6.            Harvey CJdC, Schofield GM, Zinn C, Thornley SJ, Crofts C, Merien FLR. Low-carbohydrate diets differing in carbohydrate restriction improve cardiometabolic and anthropometric markers in healthy adults: A randomised clinical trial. PeerJ. 2019;7:e6273.

7.            Layman DK, Baum JI. Dietary Protein Impact on Glycemic Control during Weight Loss. The Journal of Nutrition. 2004;134(4):968S-73S.

8.            Layman DK, Boileau RA, Erickson DJ, Painter JE, Shiue H, Sather C, et al. A Reduced Ratio of Dietary Carbohydrate to Protein Improves Body Composition and Blood Lipid Profiles during Weight Loss in Adult Women. The Journal of Nutrition. 2003;133(2):411-7.

9.            Piatti PM, Monti LD, Magni F, Fermo I, Baruffaldi L, Nasser R, et al. Hypocaloric high-protein diet improves glucose oxidation and spares lean body mass: Comparison to hypocaloric high-carbohydrate diet. Metabolism. 1994;43(12):1481-7.

10.         Farnsworth E, Luscombe ND, Noakes M, Wittert G, Argyiou E, Clifton PM. Effect of a high-protein, energy-restricted diet on body composition, glycemic control, and lipid concentrations in overweight and obese hyperinsulinemic men and women. The American Journal of Clinical Nutrition. 2003;78(1):31-9.

11.         Labayen I, Diez N, Gonzalez A, Parra D, Martinez J, editors. Effects of protein vs. carbohydrate-rich diets on fuel utilisation in obese women during weight loss. Forum of nutrition; 2002.

12.         Keller U. Dietary proteins in obesity and in diabetes. International Journal for Vitamin and Nutrition Research. 2011;81(23):125-33.

13.         Halton TL, Hu FB. The Effects of High Protein Diets on Thermogenesis, Satiety and Weight Loss: A Critical Review. Journal of the American College of Nutrition. 2004;23(5):373-85.

14.         Westerterp KR. Diet induced thermogenesis. Nutrition & metabolism. 2004;1(1):5.

15.         Johnston CS, Day CS, Swan PD. Postprandial Thermogenesis Is Increased 100% on a High-Protein, Low-Fat Diet versus a High-Carbohydrate, Low-Fat Diet in Healthy, Young Women. Journal of the American College of Nutrition. 2002;21(1):55-61.

16.         Robinson SM, Jaccard C, Persaud C, Jackson AA, Jequier E, Schutz Y. Protein turnover and thermogenesis in response to high-protein and high-carbohydrate feeding in men. The American Journal of Clinical Nutrition. 1990;52(1):72-80.

17.         Johnstone AM, Horgan GW, Murison SD, Bremner DM, Lobley GE. Effects of a high-protein ketogenic diet on hunger, appetite, and weight loss in obese men feeding ad libitum. Am J Clin Nutr 2008;87(1):44-55.

18.         Darling AL, Millward DJ, Torgerson DJ, Hewitt CE, Lanham-New SA. Dietary protein and bone health: a systematic review and meta-analysis. The American Journal of Clinical Nutrition. 2009.

19.         Cawood AL, Elia M, Stratton RJ. Systematic review and meta-analysis of the effects of high protein oral nutritional supplements. Ageing Research Reviews. 2012;11(2):278-96.

20.         Kim JE, O’Connor LE, Sands LP, Slebodnik MB, Campbell WW. Effects of dietary protein intake on body composition changes after weight loss in older adults: a systematic review and meta-analysis. Nutrition reviews. 2016;74(3):210-24.

21.         Kim JE, Sands L, Slebodnik M, O’Connor L, Campbell W. Effects of high-protein weight loss diets on fat-free mass changes in older adults: a systematic review (371.5). The FASEB Journal. 2014;28(1 Supplement).

22.         Altorf – van der Kuil W, Engberink MF, Brink EJ, van Baak MA, Bakker SJL, Navis G, et al. Dietary Protein and Blood Pressure: A Systematic Review. PloS one. 2010;5(8):e12102.

23.         Santesso N, Akl EA, Bianchi M, Mente A, Mustafa R, Heels-Ansdell D, et al. Effects of higher- versus lower-protein diets on health outcomes: a systematic review and meta-analysis. Eur J Clin Nutr. 2012;66(7):780-8.

24.         Helms ER, Zinn C, Rowlands DS, Brown SR. A Systematic Review of Dietary Protein during Caloric Restriction in Resistance Trained Lean Athletes: A Case for Higher Intakes. International Journal of Sport Nutrition and Exercise Metabolism. 2014;24(2):127-38.

25.         Pasiakos SM, Lieberman HR, McLellan TM. Effects of Protein Supplements on Muscle Damage, Soreness and Recovery of Muscle Function and Physical Performance: A Systematic Review. Sports Medicine. 2014;44(5):655-70.

26.         Pasiakos SM, McLellan TM, Lieberman HR. The Effects of Protein Supplements on Muscle Mass, Strength, and Aerobic and Anaerobic Power in Healthy Adults: A Systematic Review. Sports Medicine. 2015;45(1):111-31.