There were several principal findings. First, both the AED and NFD groups experienced significant weight loss at 6 (7%) and 18 (5%) mo. These amounts of weight loss are similar to those observed in other studies (4
) but less than that in one study (20
) that incorporated nuts into a weight-management program. The greater weight loss seen in that study (20
) could have been the result of the inclusion of a portion-controlled (liquid formula) diet in both groups or a low-carbohydrate diet in the nut group only, both of which have been shown to have significant effects on short-term weight loss without the incorporation of nuts (27
The NFD group experienced slightly (1.9%) but significantly greater reductions in weight than did the AED group at 6 mo. These findings were in the opposite direction of our hypothesis and may be secondary to the NFD group choosing foods lower in calories for snacks than nuts, which resulted in slightly greater energy deficits. No statistically significant differences in body weight were found between the groups at 18 mo. Whereas the difference between the groups was approximately the same at 6 and 18 mo (1.5 kg compared with 1.8 kg), the variability was greater at 18 mo. The clinical significance of the small difference in weight between groups at 6 or 18 mo (~2%) is unclear, particularly given the lack of differences in body composition between the groups at either 6 or 18 mo. Both groups experienced minimal weight regain (1%) between 6 and 18 mo. Given that the frequency of the group sessions decreased over time, adherence to both diets may have declined.
The second principal finding was that, despite the slightly smaller weight losses at 6 mo in the AED group, triglycerides, TC, and TC:HDL cholesterol improved more in the AED group than in the NFD group. Specifically, the AED group had a 4% greater reduction in TC and a 12% greater reduction in triglycerides than did the NFD group at 6 mo. The changes are notable given that baseline lipid profiles were close to optimal ranges, which left a restricted range for improvement and/or differences between groups.
A trend toward a greater reduction in VLDL cholesterol in the AED group was observed at 6 mo, consistent with an effect (at 6 mo) of either reduced hepatic VLDL production or increased VLDL lipolysis. Finally, at 6 mo, TC:HDL cholesterol decreased significantly more in the AED group (−0.2 ± 0.1) than in the NFD group (0.04 ± 0.1), consistent with a cardioprotective effect. As in our study, Wien et al (20
) found reductions in LDL cholesterol across groups but no differences between intervention groups. In our sample, the effects of almonds on LDL may have been attenuated by the effects of weight loss on LDL. Furthermore, the elevated BMI in our sample may have limited the potential cholesterol-lowering effects of nut consumption, which pooled analyses suggest to be more effective in individuals with a lower BMI (5
Mechanistically, the compositional properties of almonds that contribute to improvements in triglycerides and TC remain unclear; however, as above, they appear to be related to effects on VLDL metabolism. Almonds are rich in unsaturated fatty acids, which can influence VLDL metabolism (30
). The reduction in triglycerides and cholesterol might be expected to reduce cardiovascular disease risk if maintained over a long time (32
To our knowledge, this was the longest and largest study to date on almond consumption in the context of a weight-management program. Both groups achieved significant short-term weight reduction, which was generally maintained at 18 mo. Our study was conducted primarily with female participants, so generalization to males should be conducted with caution. It was also conducted outside of a metabolic ward, precluding objective assessments of dietary adherence, except weight loss. Whereas adherence to intake and activity were discussed in groups, data were not collected in any standardized manner. Self-reported data have been shown to be invalid when compared with objective measures such as doubly labeled water (33
). The differences in lipid profiles at 6 mo, in the context of comparable weight loss, suggested that patients adhered to the energy-deficit diet and to the instruction to consume almonds (AED) or avoid nuts (NFD). The lack of lipid differences at 18 mo suggests decreased adherence over time.
In conclusion, incorporating limited portions of almonds—an energy-dense food—into a behavioral weight-loss program still resulted in significant weight reduction. Moreover, despite a smaller weight loss at 6 mo in comparison with the NFD group, the AED group experienced greater improvements in cardiovascular disease risk factors. There were no differences in weight loss or cardiovascular disease risk factor outcomes between groups at 18 mo.