Dietary Approaches to Stop Hypertension-style (DASH Pattern) and Mediterranean-style (MED Pattern) eating patterns are considered “healthy eating patterns” (HEPs) among others [1
]. The DASH and MED HEPs are high in fruits, vegetables, whole grains, and lean protein sources and limited in full-fat dairy products, red meats, and refined grains [3
]. The DASH Pattern is a well-established non-pharmacological approach to reduce blood pressure and also improves total and low-density lipoprotein (LDL) cholesterol concentrations [5
]. Adherence to a MED pattern is consistently associated with reduced risk of cardiovascular disease (CVD) and related mortality [6
] and improves CVD risk factors [8
Adhering to HEPs promotes cardiovascular health, but long-term HEP adherence is poor, often short-lived, and can lead to repetitive attempts of adopting—but not successfully maintaining—HEPs [9
]. While CVD risk factors are responsive to short-term dietary changes [12
], it is unknown how repeated cycles of adopting, abandoning, and readopting recommended HEPs (i.e., HEP cycling) influence cardiovascular health. Investigating HEP cycling is warranted, in part, due to possible similarities to weight cycling previously shown to increase CVD risk and related-mortality [17
]. In a novel approach to assess the effects of HEP cycling on CVD risk factors, a secondary analysis was conducted by pooling data from two randomized crossover controlled feeding trials that included a four-week washout period between two HEP interventions: the DASH Study [20
] and the MED Study [21
]. We hypothesized that (1) adopting HEPs would improve CVD risk factors, (2) abandoning HEPs would reverse improvements in CVD risk factors from initial HEP adoption, and (3) the magnitude of changes in CVD risk factors would not differ between initial and subsequent HEP adoption.
These results emphasize that CVD risk factors are sensitive to short-term dietary changes but are the first, to the best of our knowledge, to show that HEP cycling is not detrimental to subsequent improvements in most CVD risk factors. Consuming HEPs, such as a DASH or MED Pattern, improves CVD risk factors within 5–6 weeks, but these improvements are lost within four weeks of abandonment. Individuals can improve most CVD risk factors to a comparable extent by readopting HEPs. Our research emphasizes the importance of consistently consuming HEPs for cardiovascular health.
Our results support previous research showing that consuming a DASH Pattern or MED Pattern improves CVD risk factor profiles. Blood pressure improvements during the DASH and MED HEP interventions (up to −6 and −4 mm Hg for systolic and diastolic blood pressure, respectively) were comparable to the original randomized 8-week DASH [12
] and 3-month MED [27
] Pattern controlled trials. Reductions in total, LDL, and HDL in our 5–6 week study (−19, −13, and −4 mg/dL, respectively) were comparable to the original 8-week DASH trial [28
] (−14, −11, and −4 mg/dL, respectively) and twice the magnitude which occurred in the original three-month MED trial [27
] (−5, −6, and −2 mg/dL, respectively). Therefore, HEPs are effective short- and longer-term non-pharmacologic approaches to decrease indicators of CVD risk [3
], but additional lifestyle modifications, such as weight loss or exercise may be needed to improve glycemic control [29
Participants’ CVD risk factors returned to baseline values from abandoning HEPs for four weeks, highlighting the importance of sustained HEP consumption. Previous research shows that self-reported adherence to prescribed eating patterns drops ~10% each month with participants being <40% adherent after 6 months of a dietary intervention [31
]. Eating behavior is affected by a complex set of behavioral, biological, environmental, and psychosocial factors that makes long-term HEP adherence difficult for most people [32
]. Health-related behaviors are also driven largely by routines and habits, and altering those behaviors relies extensively on executive brain function. However, executive functioning is effortful and prone to error, especially in difficult environments and/or circumstances [33
] such as ready access to inexpensive, energy dense, and palatable foods [34
]. Changes in current food environments are needed to ease consistent consumption of HEPs to avoid fluctuations in cardiovascular health.
We observed comparable improvements in CVD risk factors when participants readopted HEPs after a period of self-selected eating, except LDL concentrations. LDL concentrations did not differ between baseline 1 and baseline 2, but decreases were blunted during HEP 2 compared to HEP 1. Similar results occurred in a study designed to assess the effects of weight cycling on CVD risk factors in non-obese young women. During the first and second 4-week energy-restricted periods, LDL concentrations decreased by −18.8 ± 7.7 and −9.2 ± 1.1 mg/dL, respectively, compared to initial baseline values [35
]. These results combined with ours indicate that improvements in LDL concentrations were blunted by ~100% during a second attempt to either lose weight or consume a HEP. Interventional studies are needed to assess whether 3+ repeated cycles of HEP cycling further inhibit improvements in LDL concentrations as well as long-term consequences of repeated HEP cycles on CVD onset and related events.
Weight cycling commonly causes individuals to regain more body mass than initially lost, causing an upward “drift” in baseline body mass [18
]. The current results show a downward baseline body mass drift during one HEP cycle with a prescribed four-week period of HEP abandonment. During the washout period, participants regained about half of the body mass initially lost, resulting in a lower value at baseline 2 than baseline 1. This downward “drift” in body mass likely explains the blunted body mass decrease observed when participants readopted HEPs compared to initial adoption. It is unclear if blunted decreases in body mass were related to blunted decreases in LDL during HEP 2. Exploratory post hoc assessments revealed that changes in body mass were correlated with changes in LDL (r2
= 0.10, p
= 0.0036) and total cholesterol (r2
= 0.10, p
= 0.0010) but not correlated with other CVD risk factors. There was no difference in the magnitude of body mass loss between the two energy restricted periods in the study mentioned previously that showed similar patterns in LDL changes [35
]. Therefore, caution is warranted with regard to whether the blunted LDL response during HEP 2 may be explained by changes in body mass.
Data for this secondary analysis were pooled from two randomized crossover controlled feeding trials [20
] in which each participant consumed prescribed HEPs during two separate intervention periods. The dietary control achieved may be considered a strength and a limitation. Tightly controlled short-term feeding trials in which some or all of the foods are provided to participants allow researchers to assess the efficacy of eating patterns on cardiovascular health. However, adherence to eating patterns is lower when participants are counseled on what foods to consume compared to when food is provided [37
]. Therefore, changes in CVD risk factors may not be as apparent if participants were not prescribed menus and provided foods. The present study was limited by measuring CVD risk factors at only four time points. In the original DASH trial, blood pressures dropped after two weeks of participants consuming a DASH Pattern and then stabilized for the remaining eight-week intervention [12
]. Future studies should measure CVD risk factors more frequently to assess when changes occur during HEP cycling. Future research should also consider timing and frequency of HEP consumption, as higher meal/snack frequency is associated with better cardiovascular health [38