BACKGROUND: Patients on dietary, weight-reducing treatment commonly are advised against alcohol consumption. In light of the widespread use of alcoholic beverages and the well-established benefits of light to moderate alcohol consumption in risk reduction, a revision of dietary treatment recommendations may be warranted.
OBJECTIVE: To investigate whether daily consumption of moderate amounts of alcohol influences the effectiveness of an energy-restricted diet in overweight and obese subjects.
DESIGN: A prospective randomized clinical trial was conducted, with a 3-months intervention period and two isocaloric dietary regimens containing 6.3 MJ (1500 kcal) each, one with 10% of energy from white wine and one with 10% of energy from grape juice. The trial was performed in obese subjects being recruited from the Obesity Outpatient Clinic at the University Hospital, Ulm, who all habitually consumed moderate amounts of alcohol. Out of 87 patients, 49 were eligible to participate and 40 completed the study (age 48.1±11.4 y, BMI 34.2±6.4 kg/m2). Efficacy parameters were body weight and biomarkers of good health.
RESULTS: All subjects achieved significant body weight reduction. Weight loss in the grape juice group and white wine group was 3.75±0.46 and 4.73±0.53 kg, respectively. Percent body fat, waist circumference, blood pressure, blood glucose, insulin, triglycerides, and cholesterol were reduced. The antioxidant status was unchanged, as were liver enzyme activities and other safety parameters. There were no significant differences between the groups.
CONCLUSIONS: An energy-restricted diet is effective in overweight and obese subjects used to drinking moderate amounts of alcohol. A diet with 10% of energy derived from white wine is as effective as an isocaloric diet with 10% of energy derived from grape juice.
Patients on dietary, weight-reducing treatment commonly are advised against alcohol consumption, because alcohol abuse is associated with considerable risk of morbidity and mortality.1 However, there is good epidemiologic evidence that regular moderate alcohol consumption is associated with a low risk of major coronary heart disease events2 and total mortality in the general population,3, 4 and in diabetic subjects an inverse association between alcohol consumption and mortality from coronary heart disease and from all causes has been reported.5, 6 Furthermore, it has been shown that moderate alcohol consumption is associated with a lower risk of development of type 2 diabetes.7, 8 A revision of dietary treatment guidelines to include appropriate use of alcohol, instead of a strict abstinence policy, may be warranted in light of the widespread use of alcoholic beverages and the well-established benefits of light to moderate alcohol consumption in risk reduction.
To our knowledge, there are no data available on the effectiveness of an energy-restricted diet on weight loss in subjects who habitually consume alcohol and who are not willing to omit alcohol intake while slimming. The aim of this study was to investigate the effectiveness of an energy-restricted diet on weight loss in overweight and obese subjects who regularly consume moderate amounts of alcohol. We also investigated whether there was any impairment of the effectiveness of the diet in subjects consuming alcohol during dietary treatment compared to subjects with no alcohol consumption. Subjects were given a diet with 10% of total energy intake derived from either grape juice or white wine. We examined whether there were any differences between the diet groups in weight loss, and biochemical health parameters between the groups after a 3-month intervention period.
The patients were recruited from the Obesity Center at the outpatient clinic of the University Hospital, where they had been transferred because of overweight problems. The patients were informed that the purpose of the study was to compare the effectiveness of two diet plans, one with white wine, and one with grape juice. The study was approved by the Ethics Committee at the University of Ulm.
Men and women aged >18 y with body mass index between >25.0. and ≤40.0 kg/m2 who regularly consumed 20–30 g alcohol per day and who were willing to be randomly assigned to study groups and to follow the program protocol. All subjects who had given their written informed consent were invited to participate in the study.
Individuals with a history or presence of significant disease, endocrine disorders, psychiatric diseases, alcohol or drug abuse, or abnormal laboratory test results of clinical significance were excluded. In addition, women were excluded if they were lactating, pregnant or wished to become pregnant.
Out of 87 patients, 49 patients were randomly assigned to two different diets providing 1500 kcal/day each. One group of patients was given a diet with 200 ml of white wine per day and the other group was instead given 200 ml of grape juice. All subjects enrolled in the study were wine-drinkers. White wine was specifically chosen, because it is the preferred form of wine in the geographical region of Southern Germany from where the subjects came. Additional alcoholic beverages were not allowed during the study.
The study was a prospective parallel intervention trial, in which patients were randomly assigned to one of two dietary treatment groups, a white wine (WW) group and a grape juice (GJ) group. Patients were analyzed according to their group assignment.
The dietary intervention was structured such that a staff nutritionist designed the diet regimen, explained the diet plan in detail, and counseled participants. Throughout the study, patients were prescribed a balanced diet providing 6.3 MJ/day (1500 kcal/day), with 15% of energy as protein, 30–35% of energy as fat, complemented with either 50–55% of energy as carbohydrates including grape juice, or complemented with 45–50% of energy as carbohydrates and approximately 10% of energy from white wine (200 ml=0.57 MJ [136 kcal]). Thus, 10% of energy came from either grape juice or white wine. The energy deficit was 2.1–2.9 MJ (500–700 kcal)/day. The subjects made 7-day dietary diaries the week before they visited the hospital. The diaries were analyzed and subjects were advised if needed.
After a screening visit, patients were seen monthly in the morning after an overnight fast. Body weight was measured to the nearest 0.1 kg using the same precision scale with patients dressed in underwear. Waist and hip circumferences were measured to the nearest 0.5 cm using a nonstretchable tape measure. Sagittal diameter was determined using an abdominal caliper to measure supine height of the abdomen. Body composition was measured by bioelectrical impedance analysis. Blood pressure was measured on the upper right arm using a mercury column manometer to the nearest 5 mmHg with the patient in a supine position after the patient had rested for at least 10 min. Measurements were made at each visit under similar conditions. At baseline and after 3 months, blood samples were drawn at 0800 after an overnight fast. Biochemical and safety measurements were performed by standard methods in the Department of Clinical Chemistry at the University Hospital. Liver functions tests (ALT, AST, AP, GT), creatinine, leucocytes, erythrocytes and hemoglobin were performed with routine methods. Total cholesterol was measured by enzymatic colorimetric methods using kits (Boehringer Mannheim GmbH, Mannhein, Germany). HDL-cholesterol was measured after precipitation with polyanions. Triglycerides were measured enzymatically using kits (Boehringer Mannheim GmbH, Mannheim, Germany). Blood glucose was measured enzymatically (GOD)/amperometrically (H2O2). Serum insulin was measured using an enzymometric immunoassay AIA-Pack IRI (Tosoh Corporation, Tokyo, Japan). Fibrinogen, uric acid and leucocytes were measured by standard methods.
Measurements of Vitamin C radicals as a parameter of antioxidant status were performed in the Department of Biochemistry and Nutrition at the University of Hohenheim by ESR-Spectroscopie using MiniScope MS 200 (Magnettech GmbH, Berlin, Germany).
Patients who did not complete the study, were replaced by others, until in each group 20 patients had completed the 3 months study.
Comparison of baseline values between the two different groups of patients, one with white wine and one with grape juice exchanged, were calculated by using a two-sample t-test. A paired t-test was used to test whether there were significant changes from baseline to 3 months for each group. The comparison between 3 months changes between GJ and WW, was performed with a two-sample t-test. Values are given as means±s.e.m.
Out of 87 patients, 49 agreed to participate and were randomly assigned to Group GJ or to Group WW. Nine patients withdrew prior to the end of the study due to professional, familial, and social reasons. Patients who dropped out were replaced. Overall, 20 patients in each group completed the study. Baseline characteristics of the patients are given in Table 1. None were smokers, and all habitually consumed moderate amounts of alcohol.
Subjects assigned to the WW group modestly had higher age and greater BMI compared with subjects of the GJ group, but the differences were not statistically significant between the groups. The drop-out subjects were not included in the analysis, since we aimed to investigate whether white wine, added isocalorically to an energy-restricted diet, influenced weight loss.
All the subjects reduced their body weight (Figure 1). In the GJ group weight loss was 3.75±0.46 kg (range 0.90–8.00 kg) or 4.0% of initial body weight (P<0.001). In the WW group, weight loss was 4.73±0.53 kg (range 0.90–11.70 kg) or 4.88% of initial body weight (P<0.001). The weight loss in the WW group was 26.1% greater than in the GJ group, but the difference was not significant. BMI, sagittal diameter, waist circumference, hip circumference, thigh circumference, and fat mass were reduced in both groups. Statistically significant differences between the GJ group and the WW group were not observed (Table 2).
The subjects were prescribed a diet containing 6.3 MJ (1500 kcal)/day. The analysis of self-reported 7-day diaries showed that the subjects adhered to the diet plan. Between the groups there was no difference, except that in the WW group the carbohydrates were lower than in the GJ group because of their white wine consumption (Table 3).
Blood glucose, insulin, and triacylglycerol was reduced with weight loss, but there were no significant changes in the GJ group or in the WW group. Total cholesterol was reduced, the reduction being significant only in the GJ group (P<0.05).
HDL-cholesterol and fibrinogen did not change significantly in either group. The uric acid level was modestly higher after the weight reduction in the WW group (P<0.05), but in all subjects the values were well below the upper limit of normal (Table 4).
The safety parameters (Table 5) did not change significantly after the weight reduction in both groups.
The results of this prospective controlled comparison trial showed that an energy-restricted diet was effective in overweight and obese subjects who habitually consume moderate amounts of alcohol and who maintained their habit during treatment with an energy-restricted diet.
The energy content of the prescribed diet was 6.3 MJ (1500 kcal)/day and within 90 days a weight loss of 4.5% of initial weight was achieved. Thus, most of the patients satisfactorily had observed the diet prescriptions and had lost a significant amount of body weight. In this trial, all the subjects entering the study practiced moderate alcohol consumption, but all agreed to be randomized into two groups with an energy-restricted diet, one with and one without white wine for a study period of 3 months. The results of the study provide empirical justification for the integration of moderate amounts of alcohol into an energy-restricted diet for those obese subjects who habitually drink alcohol and are not ready to quit their alcohol consumption during dietary treatment.
The study was performed with subjects who were accustomed to drink alcohol in moderate amounts, therefore the results may not be applicable to subjects with alcohol abuse. In this context it must be stressed that moderate alcohol intake has been defined as no more than one drink per day for most women and no more than two drinks per day for men,9 and that physicians and nutritionists must exercise caution in recommending alcohol use, since it may lead to overuse. Nonetheless, we feel that there is a need to recognize that energy derived from alcoholic beverages is a significant component of human nutrition. The estimated alcohol contribution to the diet in the US accounts for 5.6% of total energy.10 In Germany, 80% of men and 55% of women drink alcohol regularly. In all, 55% of the adults consume alcohol up to 10 g/day, and 28.5% consume 10–40 g alcohol per day. Thus, alcohol consumption is widespread in the population and alcoholic beverages represent part of the basic food supply.4
There is a contentious ongoing debate in the literature on the effectiveness of energy derived from alcohol. In subjects consuming substantial amounts of alcohol, adding ethanol to the diet did not change body weight. In addition, isocaloric substitution of carbohydrates with ethanol induced decrease of body weight.11 These observations led to the assumption that energy from alcohol does not count for energy balance. Consistent with this assumption, in two large cross-sectional surveys moderate alcohol consumption in women was associated with lower body weight compared to women who do not drink, an association which was not observed in men.12, 13 However, in a prospective study of men in British towns, BMI significantly increased with alcohol intake14 and in consecutive cross-sectional surveys over 15 y in Finland in men, BMI increased with increasing alcohol consumption but decreased in women.15 In the German National Health Survey, 1998, among males BMI was not associated with moderate consumption of alcohol, but in females alcohol drinkers had a lower BMI than teetotalers.4 Colditz et al12 have shown that, both in men and women, alcohol consumption increased total energy intake. In men, the relation of increased energy intake with alcohol intake was more pronounced than in women. Despite increased energy intake, there was no weight gain in men, and in women increasing amounts of alcohol intake were associated with lower body weight. Thus, there is a gender difference in the relation between daily alcohol consumption and BMI. In men, there is no consistent relation whereas in women moderate alcohol intake is associated with lower body weight.
The underlying mechanisms through which alcohol intake may influence body weight are not known. It has been speculated that moderate alcohol intake increases energy expenditure, in women more than in men.16 In metabolic studies in healthy patients without heavy alcohol consumption it has been shown that the body uses alcohol energy efficiently. Using whole-body indirect calorimetry, 85% of alcohol energy is available as metabolizable energy.17 In addition, it has been reported that alcohol intake reduces fat oxidation and favours a positive fat balance.18, 19 Similarly, recent findings have shown that alcohol intake induces no, or minimal, compensation by decreasing nonalcohol food energy intake.20, 21 Therefore, energy derived from alcohol intake represents extra calorie intake and may be important for body weight control.
The prescribed diet in the present study included either 10% of energy derived from grape juice or 10% derived from white wine. The energy content of both diets was isocaloric. In accord with the low-energy content in both diets there was a weight loss of 4.0 and 4.9% of initial body weight, respectively. The thesis of the study, that moderate amounts of white wine integrated in an energy-restricted diet regimen do not impair the effectiveness of the energy-restricted diet, is supported by the results.
The weight loss in the group of patients with alcohol consumption even exceeded, though not significantly, that in the group without alcohol. The reason for this difference in weight loss, which may become greater with longer duration of treatment, is not known. The physical activity assessed by careful recall was similar in both groups of patients. Additionally, there were no striking differences between the groups in socioeconomic status, education, and occupation. Furthermore, there were no reports from the subjects indicating maldigestion, malabsorption or increased sympathetic tone and associated tachycardia.
At the beginning of the study, the body weight in the group of patients with white wine was 3.6 kg greater than in the group of patients with grape juice. Calculating the energy need22 subjects had a greater need of 0.38 MJ (90 kcal)/day, which would add up to 33.9 MJ (8100 kcal) within 3 months. Theoretically, the greater weight loss in group WW of 0.98 kg could be explained by the difference in energy need. But the WW subjects were on average 5.1 y older and calculating the reduction of energy need with age, the greater energy need with increasing body weight approximately is neutralized. Therefore, the difference in weight loss in the groups does not appear to be due to the difference in initial body weight or age in years.
The energy derived from white wine (0.64 MJ [152 kcal]/day) during the 90-days study summed up to 57.5 MJ (13 738 kcal) and under the assumption that calories derived from alcohol do not count, might explain to some extent the surplus of weight loss. However, the missing effect of alcohol-derived energy on energy balance has been described only in patients with chronic alcohol abuse and liver damage.11 The subjects in this study had no alcohol abuse and no liver disease. Therefore, there is no reason to assume that the calories from alcohol have been metabolized without associated chemical energy production.
The 6.3 MJ/day (1500 kcal) dietary regimen theoretically leads to an energy deficit of approximately 2.5 MJ/day (600 kcal). Calculating the dietary induced achievable weight loss on the basis of a daily energy deficit of 2.5 MJ (600 kcal), the expected weight loss after 90 days would be approximately 6 kg. In both groups, the observed weight loss was somewhat less than expected. This may be explained by the fact that subjects were outpatients and the adherence to the dietary prescriptions was probably lower than it would be under strict metabolic-ward conditions. Nevertheless, the subjects with white wine consumption were somewhat closer to the theoretically achievable weight loss. One could speculate that the wine drinkers had kept to the dietary prescriptions more thoroughly than the subjects with grape juice. However, an analysis of the diet diaries of the subjects could not detect significant differences between the groups. This is in accordance with previous reports that moderate alcohol consumption exerts no inhibitory effect on macronutrient intakes.23, 24
Subjects with type 2 diabetes or with the metabolic syndrome commonly are overweight or obese and it may reasonably be assumed that some of them are used to moderate alcohol consumption. To reduce the metabolic complications and the cardiovascular risk in these patients, weight reduction is needed. Appropriate dietary guidelines commonly will not allow alcoholic beverages. For this reason, many of the subjects may fear prohibition and may avoid dietary treatment, in particular long-term treatment. Therefore, subjects with habitual moderate alcohol consumption should possibly be allowed to maintain their habit to diminish their objections to a dietary regimen and to improve compliance. The results of this study suggest that one ought not to be concerned that moderate alcohol consumption might impair the effectiveness of an energy-restricted diet or worsen the compliance.
In the absence of contraindications and in the context of healthy eating and lifestyle, moderate consumption of white wine may contribute to the prevention of cardiovascular events and development of type 2 diabetes. This ought to give rise to re-examination of dietary recommendations, giving appropriate advice allowing alcoholic beverages integrated in the diet. However, patients with a dietary regimen with moderate amounts of wine included should seriously and clearly be warned of the risk of overconsumption. Patients should be instructed carefully that the use of alcohol should not be misinterpreted as a prescription for weight reduction or for prevention of type 2 diabetes or cardiovascular events. Also it would always be inappropriate to recommend that nondrinkers commence drinking.
This study was done with white wine and overweight and obese healthy subjects used to moderate alcohol consumption and the results may not be applicable to all alcoholic beverages and to normal-weight subjects or subjects with liver diseases, psychiatric diseases or the risk for alcohol abuse. The number of subjects studied was small and the duration of the study was 3-months. Therefore, the statistical predictive power and ability to extrapolate from this study is limited. There is clearly a need to investigate the long-term effect of moderate alcohol consumption on weight loss and weight maintenance with a greater number of subjects to confirm and clarify our findings.
In conclusion, the results of this study indicate that overweight and obese patients with moderate alcohol consumption may be allowed to maintain their habit during dietary treatment, if they choose. Moderate amounts of white wine integrated into an energy-restricted diet regimen should not impair the effectiveness of the diet and may be helpful for weight management in some patients with obesity.
We would like to thank Katja Huber, for her excellent assistance with the collection of the data. We are grateful to Eva Hauck who performed experimental work on measuring the antioxidant status of the subjects. The study was supported by grants from Deutsche Weinakademie GmbH (D-55116 Mainz, www.deutscheweinakademie.de) and Forum Wein und Gesundheit (D-55758 Langweiler, www.wein-und-gesundheit.de). None of the authors has any type of remuneration from an interested party.
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BMC Family Practice (2005)