Plain language summary
Diets high in carbohydrates especially when consumed in sugar-sweetened food and beverages has been shown to result in increased energy intakes in the diet. However, diets low in sugar and carbohydrates have been shown to have a limited effect on changes in body mass and weight loss. In this instance, some other mechanism is preventing weight loss. Diets low in carbohydrates have been shown to decrease physical activity levels and energy expenditure, which may be responsible for the limited weight loss seen with carbohydrate restricted diets. This randomised control trial of 25 individuals aimed to determine whether carbohydrate restriction would reduce physical activity energy expenditure over a 24-hour period compared to diets higher in sugar and/or carbohydrates. Individuals with a low dietary intake of sugar and carbohydrates and moderate intake of sugar all showed similar physical activity energy expenditure levels. Interestingly low carbohydrate intake resulted in the highest 24 hour increase in low density lipoprotein concentrations and decreased satiety hormones. It was concluded that when energy density is controlled, restricting sugar or carbohydrates has no effect on physical activity levels over a 24-hour period. This study could be used by healthcare professionals that in the very short-term low sugar and carbohydrate diets have no effect on physical activity levels but does affect metabolic changes. However studies need to be performed to determine long-term effects.
Abstract
PURPOSE To determine the effects of dietary sugar or carbohydrate restriction on physical activity energy expenditure, energy intake, and physiological outcomes across 24 h. METHODS In a randomized, open-label crossover design, twenty-five healthy men (n = 10) and women (n = 15) consumed three diets over a 24-h period: moderate carbohydrate and sugar content (MODSUG = 50% carbohydrate [20% sugars], 15% protein, 35% fat); low sugar content (LOWSUG = 50% carbohydrate [< 5% sugars], 15% protein, 35% fat); and low carbohydrate content (LOWCHO = 8% carbohydrate [< 5% sugars], 15% protein, 77% fat). Postprandial metabolic responses to a prescribed breakfast (20% EI) were monitored under laboratory conditions before an ad libitum test lunch, with subsequent diet and physical activity monitoring under free-living conditions until blood sample collection the following morning. RESULTS The MODSUG, LOWSUG and LOWCHO diets resulted in similar mean [95%CI] rates of both physical activity energy expenditure (771 [624, 919] vs. 677 [565, 789] vs. 802 [614, 991] kcal·d-1; p = 0.29] and energy intake (2071 [1794, 2347] vs. 2195 [1918, 2473] vs. 2194 [1890, 2498] kcal·d-1; P = 0.34), respectively. The LOWCHO condition elicited the lowest glycaemic and insulinaemic responses to breakfast (P < 0.01) but the highest 24-h increase in LDL-cholesterol concentrations (P < 0.001), with no differences between the MODSUG and LOWSUG treatments. Leptin concentrations decreased over 24-h of consuming LOWCHO relative to LOWSUG (p < 0.01). CONCLUSION When energy density is controlled for, restricting either sugar or total dietary carbohydrate does not modulate physical activity level or energy intake over a 24-h period (~ 19-h free-living) despite substantial metabolic changes. CLINICAL TRIALS REGISTRATION ID NCT03509610, https://clinicaltrials.gov/show/NCT03509610.
Methodological quality
Jadad score
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1
Allocation concealment
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No
