Background

Some evidence suggests that when people adopt lifestyle changes for weight management, members of their family change their behaviors as well — a phenomenon called the “halo effect”.[1][2] While several studies have explored the halo effect of bariatric surgery and dietary interventions, more research is needed on interventions that combine dietary changes and exercise.

The study

This 2-year prospective study examined the halo effect in 148 untreated family members of the 6,874 participants in a diet-and-exercise randomized controlled trial (RCT).

In the RCT,[3] 6,874 people had been randomized to either a 2-year lifestyle intervention (hypocaloric Mediterranean diet, individualized physical-activity promotion, and behavioral support) or a control group.

The 148 family members analyzed for the prospective study didn’t receive lifestyle advice; they visited a clinic or simply completed questionnaires — at baseline, one year, and two years — to assess their body weight, adherence to a Mediterranean diet, and physical activity.

The results

The family members of the people in the intervention group lost weight at one year (−1.25 kg, so −2.76 lb) and two years (−3.98 kg, so −8.77 lb), while the family members of the people in the control group gained weight at one year (+3.30 kg, so +7.28 lb) and two years (+1.90 kg, so +4.19 lb). The between-group difference was statistically significant at two years, but not at one year.

The family members of the people in the intervention group were also more likely to be following a Mediterranean diet, at both time points.

The weight changes of the people in the intervention group and the weight changes of their family members were correlated at both time points, despite the physical activity levels of the family members not having significantly changed from baseline.

Note

Several other studies have assessed the halo effect among the spouses of participants in weight-loss lifestyle interventions.

  • In a 2009 study, the spouses of participants randomly allocated to a Mediterranean, low-carb, or low-fat diet for 2 years lost 3.00 kg (6.61 lb), lost 2.30 kg (5.07 lb), and gained 0.39 kg (0.86 lb), respectively.[1]
  • In a 2008 study, the spouses of participants in a 1-year weight-loss intervention combining diet and exercise lost 2.2 kg (4.9 lb).[2]
  • In a 1992 study, the spouses of participants in a 1-year low-fat dietary intervention lost 0.95 kg (2.09 lb).[4]
  • In a 1991 study, the spouses of participants in a 6-month low-fat dietary intervention lost 1.1 kg (2.4 lb).[5]
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This Study Summary was published on May 4, 2021.

References

  1. ^Rachel Golan, Dan Schwarzfuchs, Meir J Stampfer, Iris Shai, DIRECT groupHalo effect of a weight-loss trial on spouses: the DIRECT-Spouse studyPublic Health Nutr.(2010 Apr)
  2. ^A A Gorin, R R Wing, J L Fava, J M Jakicic, R Jeffery, D S West, K Brelje, V G Dilillo, Look AHEAD Home Environment Research GroupWeight loss treatment influences untreated spouses and the home environment: evidence of a ripple effectInt J Obes (Lond).(2008 Nov)
  3. ^Miguel A Martínez-González, Pilar Buil-Cosiales, Dolores Corella, Monica Bulló, Montserrat Fitó, Jesús Vioque, Dora Romaguera, J Alfredo Martínez, Julia Wärnberg, Jose López-Miranda, Ramón Estruch, Aurora Bueno-Cavanillas, Fernando Arós, Josep A Tur, Francisco Tinahones, Lluis Serra-Majem, Vicente Martín, Jose Lapetra, Clotilde Vázquez, Xavier Pintó, Josep Vidal, Lidia Daimiel, Miguel Delgado-Rodríguez, Pilar Matía, Emilio Ros, Fernando Fernández-Aranda, Cristina Botella, María Puy Portillo, Rosa M Lamuela-Raventós, Ascensión Marcos, Guillermo Sáez, Enrique Gómez-Gracia, Miguel Ruiz-Canela, Estefania Toledo, Ismael Alvarez-Alvarez, Javier Díez-Espino, José V Sorlí, Josep Basora, Olga Castañer, Helmut Schröder, Eva María Navarrete-Muñoz, Maria Angeles Zulet, Antonio García-Rios, Jordi Salas-Salvadó, PREDIMED-Plus Study InvestigatorsCohort Profile: Design and methods of the PREDIMED-Plus randomized trialInt J Epidemiol.(2019 Apr 1)
  4. ^A L Shattuck, E White, A R KristalHow women's adopted low-fat diets affect their husbandsAm J Public Health.(1992 Sep)
  5. ^E White, M Hurlich, R S Thompson, M N Woods, M M Henderson, N Urban, A KristalDietary changes among husbands of participants in a low-fat dietary interventionAm J Prev Med.(Sep-Oct 1991)