Acid-base safety during the course of a very low-calorie-ketogenic diet

Endocrine. 2017 Oct;58(1):81-90. doi: 10.1007/s12020-017-1405-3. Epub 2017 Sep 15.


Background and aims: Very low-calorie ketogenic (VLCK) diets have been consistently shown to be an effective obesity treatment, but the current evidence for its acid-base safety is limited. The aim of the current work was to evaluate the acid-base status of obese patients during the course of a VLCK diet.

Method: Twenty obese participants undertook a VLCK diet for 4 months. Anthropometric and biochemical parameters, and venous blood gases were obtained on four subsequent visits: visit C-1 (baseline); visit C-2, (1-2 months); maximum ketosis; visit C-3 (2-3 months), ketosis declining; and visit C-4 at 4 months, no ketosis. Results were compared with 51 patients that had an episode of diabetic ketoacidosis as well as with a group that underwent a similar VLCK diet in real life conditions of treatment.

Results: Visit C1 blood pH (7.37 ± 0.03); plasma bicarbonate (24.7 ± 2.5 mmol/l); plasma glucose (96.0 ± 11.7 mg/l) as well as anion gap or osmolarity were not statistically modified at four months after a total weight reduction of 20.7 kg in average and were within the normal range throughout the study. Even at the point of maximum ketosis all variables measured were always far from the cut-off points established to diabetic ketoacidosis.

Conclusion: During the course of a VLCK diet there were no clinically or statistically significant changes in glucose, blood pH, anion gap and plasma bicarbonate. Hence the VLCK diet can be considered as a safe nutritional intervention for the treatment of obesity in terms of acid-base equilibrium.

Keywords: Acidosis; Acid–base safety; Ketogenic diet; Ketosis; Obesity; Very low-energy diet.

Publication types

  • Clinical Trial

MeSH terms

  • Acid-Base Imbalance / etiology
  • Acid-Base Imbalance / metabolism*
  • Adult
  • Anthropometry
  • Bicarbonates / blood
  • Blood Gas Analysis
  • Blood Glucose
  • Caloric Restriction / adverse effects*
  • Diabetic Ketoacidosis / blood
  • Diet, Ketogenic / adverse effects*
  • Diet, Reducing
  • Female
  • Humans
  • Hydrogen-Ion Concentration
  • Ketone Bodies / blood
  • Ketosis / blood
  • Ketosis / chemically induced
  • Male
  • Middle Aged
  • Obesity / diet therapy*
  • Obesity / metabolism
  • Weight Loss


  • Bicarbonates
  • Blood Glucose
  • Ketone Bodies