Severe carbohydrate restriction not necessary for ketosis, weight loss in low-energy diets
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Key takeaways:
- All low-energy diets achieved ketosis, regardless of carbohydrate quantity.
- Although the low-carbohydrate group achieved more weight loss, there was no significant difference in hunger between the groups.
Low-energy diets that included up to 130 g per day of carbohydrates still induced weight loss in association with ketosis without the expected increase in hunger among adults with obesity, according to a study published in Obesity.
Ketogenic diets, used for weight loss, limit carbohydrate intake to less than 50 g per day, restricting access to core food groups, which may in turn increase risk for the development of diseases such as cancer and cardiovascular disease.
“The ability to maximize carbohydrate intake while preventing the increase in hunger would allow individuals seeking weight loss to increase food choices and expand diet variety, particularly nutrient-dense carbohydrate-containing foods, which have proven to be beneficial for health,” Jessica A. Roekenes, a PhD candidate in the department of clinical and molecular medicine at Norwegian University of Science and Technology in Trondheim, Norway, and colleagues wrote.
Researchers investigated the impact of three low-energy diets with different amounts of carbohydrates on ketosis and changes in hunger among adults with obesity.
The multiarmed, single-center, single-blind study included 101 healthy, weight-stable adults aged 18 to 65 years (women, n = 51) with obesity (mean BMI, 34.7 kg/m2) who were not actively trying to lose weight.
Researchers randomly assigned the participants to a low-energy diet (1,000 kcal/day) with one of three levels of carbohydrates: low (n = 34; 70 g/day), medium (n = 34; 100 g/day) or high (n = 33; 130 g/day). Participants underwent their respective low-energy diets for 8 weeks followed by 4 weeks of gradual refeeding and weight stabilization.
The primary endpoint was changes in feeling of hunger, assessed with visual analog scales. Secondary outcomes evaluated the impact of weight loss in and out of ketosis on other appetite markers, such as feelings of fullness and concentrations of beta-hydroxybutyrate (BHB). Measurements were taken at baseline (n = 99), week 8 (n = 87) and week 12 (n = 77).
The researchers found significant weight loss across all groups. However, the low-carbohydrate group had transiently greater weight loss at week 8 compared with the medium (2.32 kg; 95% CI, 0.44-4.21; P = .016) and high (2.29 kg; 95% CI, 0.39-4.19; P = .016) carbohydrate groups.
Researchers noted all groups achieved ketosis, although there were significantly greater BHB levels in the low-carbohydrate group compared with the medium (–0.4 mM; 95% CI, –0.67 to –0.09; P < .001) and high (–0.64 mM; 95% CI, –0.84 to –0.44; P < .001) groups, with no significant difference between the medium and high group at week 8.
Notably, the participants showed no significant difference between groups in feelings of hunger, their desire to eat, prospective food consumption or fullness from baseline to either weeks 8 or 12 in both the fasting and postprandial states.
“Maximizing carbohydrate intake while preventing increased hunger ratings will allow those seeking weight loss to eat more micronutrient-rich, carbohydrate-containing foods that are beneficial for health, which is likely to improve dietary adherence and weight loss outcomes,” the researchers wrote.
They noted several limitations to the study, including that it was underpowered to definitively conclude that there were no differences in hunger ratings between the groups.
“Although these results are not definitive, they suggest that, in adults with obesity, low-energy diets with prescriptions of 1,000 kcal/day and 130 g/day of carbohydrates or greater can induce clinically significant weight loss in association with ketosis, without the expected increase in hunger feelings typically observed,” the researchers wrote.
Future studies should be performed with these conditions to replicate these results, they added.
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