Beverage Consumption and Adult Weight Management: A Review

1. Introduction

Caloric intake has increased over the past 20 years, with the majority of the increase derived from snacks foods (Nielsen, Siega-Riz, & Popkin, 2002) and beverages (Duffey & Popkin, 2007). Beverage consumption patterns in children and adolescents are an important _target for promoting body weight management (Ludwig, Peterson, & Gortmaker, 2001; Sanigorski, Bell, & Swinburn, 2007), yet until recently, less attention has been directed at beverage consumption and adult weight management. The potential negative public health consequences of sweetened beverage consumption have led some to suggest a sugar-sweetened beverage tax (Brownell & Frieden, 2009), which is controversial due in part to a lack of direct evidence linking changes in sweetened beverage intake to weight outcomes (Allison & Mattes, 2009). Thus, the purpose of this article is to review literature addressing beverage consumption and adult weight management.

Though beverages of all types satisfy thirst (Almiron-Roig & Drewnowski, 2003), caloric (i.e., energy-containing) beverages do not effect food intake during acute meal settings (Almiron-Roig & Drewnowski, 2003; DellaValle, Roe, & Rolls, 2005; Harper, James, Flint, & Astrup, 2007; Tsuchiya, Almiron-Roig, Lluch, Guyonnet, & Drewnowski, 2006). However, when compared to water or energy-free, artificially-sweetened beverages, consumption of energy-containing beverages increases total meal energy intake (Almiron-Roig & Drewnowski, 2003; DellaValle et al., 2005). The low satiety value of beverages may be explained by the fact that for most of human evolutionary history, water was the only beverage consumed (Wolf, Bray, & Popkin, 2008); regulation of beverage energy was not of biological importance. Though the exact mechanism of this weak satiety response is unclear, there are several possibilities. First, relative to solid foods, beverages take less time to consume and are rapidly emptied from the stomach (Kissileff, 1985). This is supported by research demonstrating that consumption of an isocaloric liquid compared with solid food given prior to an ad libitum meal increases food intake (Stull, Apolzan, Thalacker-Mercer, Iglay, & Campbell, 2008). Second, food form (i.e. solid vs. liquid) influences appetite-related hormonal response (Tieken et al., 2007). Finally, energy-containing beverages are largely comprised of carbohydrates, which stimulate fewer satiety signals than fat or protein (Wolf et al., 2008).

Because energy from beverages is less satiating than consumption of solid foods (DiMeglio & Mattes, 2000; R. Mattes, 2006; R. D. Mattes, 1996; Stull et al., 2008), consumption of energy-containing beverages may produce weight gain (Ludwig et al., 2001). Trends in beverage consumption coinciding with increases in overweight and obesity support this possibility; energy intake from sweetened beverages (i.e., soft drinks and fruit drinks) has increased by 222 kcal in recent decades (Duffey & Popkin, 2007). Adults with a high energy-containing beverage intake consume less healthy diets (Duffey & Popkin, 2006; Popkin, Barclay, & Nielsen, 2005), while water consumers ingest less total energy (Duffey & Popkin, 2006; Popkin et al., 2005). Soft drinks are the single greatest energy source (i.e., 7% total energy) in the American diet (Block, 2004); average daily consumption of soft drinks is > 12.3 fl oz per person (Wolf et al., 2008). Therefore, beverage consumption patterns may be an important dietary factor influencing adult weight management.

This review was conducted using a PubMed (National Library of Medicine) online literature search to identify publications (within 15 years) investigating beverage consumption and either food/energy intake or body weight management. A small number of less recent publications were included if they were a key reference for later work on this topic. Articles were limited to those published in English, and in adults. Findings were categorized according to beverage type as follows: water, other energy-free beverages (artificially sweetened beverages, coffee and tea), and energy-containing beverages (soft drinks, juice and juice drinks, milk and soy beverages, alcohol). Details of studies reviewed are presented in the Table in alphabetical order by first author’s name within each subsection. Research findings are summarized within the text in the following order: epidemiological research, test meal/short-term feeding studies, and randomized controlled trials (if available). Relevant meta-analyses and reviews are also presented.

2. Water

There is a common belief that water ingestion facilitates weight management. Epidemiological data indicate that energy intake among water drinkers is ~9% (194 kcal/d) lower than non-water drinkers (Popkin et al., 2005), yet few studies have directly addressed the effect of increased water consumption on weight management. Water consumed before or with a meal reduces sensations of hunger and increases satiety among nonobese adults (Lappalainen, Mennen, van Weert, & Mykkanen, 1993; Van Walleghen, Orr, Gentile, & Davy, 2007). However, young, normal weight men consume the same amount of energy at an ad libitum meal when given water (8 and 16 fl. oz) as compared to no beverage 30 minutes prior to the meal (Rolls et al., 1990). Pre-meal water consumption reduces meal energy intake in nonobese older adults (Van Walleghen et al., 2007), and also among middle-aged and older overweight/obese adults (Davy, Dennis, Dengo, Wilson, & Davy, 2008). Thus, it appears ingesting water (~16 fl oz) prior to a meal reduces meal energy intake among middle-aged and older adults by ~75-90 kcals, but may not impact meal energy intake among younger population segments (Davy, Dennis, Dengo et al., 2008; Van Walleghen et al., 2007).

Longer term studies have investigated changes in self-reported beverage intake to energy intake and weight during a weight loss intervention (see Table) (Stookey, Constant, Gardner, & Popkin, 2007). Over 12 months, drinking ≥1 L water (>33.8 fl oz) per day increased weight loss by ~ 2 kg as compared to drinking less water (Stookey, Constant, Popkin, & Gardner, 2008). However, these investigations relied on self-reported data and to date, no clinical intervention studies have assessed the influence of increased water consumption on weight loss in adults; the aforementioned intervention compared popular weight loss diets and water/beverage consumption was not the primary focus. Preliminary data suggests increasing daily water intake may facilitate long term weight loss among middle-aged and older adults (Davy, Dennis, Akers, Dengo, & Davy, 2008); a trend (p=0.09) was detected for greater weight loss after 6 months among individuals (n=20) following a hypocaloric diet along with three 500-ml bottled water per day (16.9 fl oz) as compared to those in a diet-only control condition. Additional long term studies with larger sample sizes are needed to confirm this possibility.

There may be other benefits of water consumption for weight management, such as increased metabolic rate (Boschmann et al., 2003; Brown, Dulloo, & Montani, 2006). Additional research is needed to confirm these findings, as well as to address issues of optimal volume and timing of water ingestion for managing hunger and reducing meal energy intake.

The Beverage Guidance Panel provided an overview of the nutritional benefits and risks of different beverage categories, and provided recommendations for beverage intake in relation to weight status and health (Popkin et al., 2006). These recommendations were controversial, in that not all were supported by scientific data (Kaplan, 2006; Weaver et al., 2006). Though there is not a Recommended Daily Allowance (RDA) for total water intake due to insufficient evidence and individual variability, the Institute of Medicine’s Food and Nutrition Board suggested a Daily Recommended Intake (DRI) for adult males and nonpregnant, nonlactating females over 19 years of 3.7 L/day and 2.7 L/day, respectively. However, this includes total water from all beverages such as coffee, tea, juices, soda and water, as well as moisture from foods (Panel on Dietary Reference Intakes for Electrolytes and Water, 2004). An Adequate Intake (AI) of 3.0 L/day for men and 2.2 L/day for women (~104 fl oz and 72 fl oz) of total beverages, including water, was also recommended. These guidelines recommend that individuals be attentive to thirst cues and consume beverages with meals to maintain adequate hydration status, but do not make specific recommendations pertaining to beverage consumption and weight management. Thus, epidemiological and acute meal studies suggests a beneficial role for water consumption in reducing energy intake and promoting weight management, yet there is insufficient data from intervention studies to make conclusive evidence-based intake recommendations for water consumption.

3. Other Energy-Free Beverages

4. Energy-containing Beverages

5. Conclusions

In the US, energy intake from beverages has increased dramatically in recent decades (Nielsen & Popkin, 2004). Americans are consuming more energy from soft drinks (Block, 2004) which may be replacing water and nutrient-containing beverages such as milk. Because energy-containing beverages do not promote satiety (R. D. Mattes, 1996), intake of energy-containing beverages may be an important dietary factor contributing to weight gain. In contrast, water consumption may reduce hunger and energy intake (Davy, Dennis, Dengo et al., 2008; Stookey et al., 2007; Stookey et al., 2008; Van Walleghen et al., 2007). These benefits, as well as its low cost and wide availability, suggests that increased water consumption ( >1 L/day; >33.8 fl oz) and a reduced intake of energy-containing beverages (Stookey et al., 2008) may facilitate weight management. However, this has not been directly addressed beyond the acute meal setting.

A limited amount of research suggests that other energy-free beverages (i.e., diet soft drinks, coffee/tea) may facilitate weight management, particularly if substituted for energy-containing beverages (Stookey et al., 2008). While there may be health benefits to consuming milk, 100% fruit juice, and in moderation, alcoholic beverages, additional energy provided by these beverages must be compensated for by reducing food intake. A summary of research investigating beverage consumption (by category), acute energy intake and body weight is provided in the Figure. Due to the lack of long-term intervention studies, further research is warranted to determine if specific patterns of beverage consumption improves health and weight status.

There are a number of limitations to existing research which should be acknowledged. First, a conflict of interest may exist between financial sponsors of beverage research and researchers. Industry-sponsored research may be less likely to report unfavorable results compared to studies with no industry support (Lesser, Ebbeling, Goozner, Wypij, & Ludwig, 2007). Differences in effect sizes between industry-funded and non-funded research studies have also been reported (Vartanian et al., 2007). Therefore, financial disclosures should be considered when evaluating this literature. A second limitation, as mentioned previously, is the lack of randomized controlled trials. Available literature largely consists of epidemiological studies, which provide evidence of associations of beverage intake and weight status but not causal relationships, and from short-term feeding studies. Other limitations include possible confounding lifestyle behaviors by categories of beverage consumers (Duffey & Popkin, 2006; Popkin et al., 2005), and aging, which may independently influence gastric emptying and energy intake regulation (Davy, Dennis, Dengo et al., 2008; Van Walleghen et al., 2007).

Weight management practitioners may consider the recently proposed beverage intake guidelines (Popkin et al., 2006), and existing fluid intake recommendations. To maintain hydration, an AI of 3.0 L/day for men and 2.2 L/day for women (~104 fl oz and 72 fl oz, respectively) of total beverages is recommended, but no specific recommendations for water intake and weight management exist. An increase in the total beverage volume consumed is associated with greater weight loss during a hypocaloric diet (Stookey et al., 2008); therefore, water (> 1 L/day; >33.8 fl oz) and other energy-free beverages should be consumed to satisfy thirst and promote optimal hydration status, without increasing total energy intake. Solid fruits should be emphasized to meet fruit intake recommendations, and low-fat/non-fat dairy or soy products may be recommended to provide micronutrients while minimizing saturated fat and energy intake. Alcoholic beverages should be consumed in moderation, for those who wish to consume alcohol. Other energy-containing beverages (i.e., soft drinks, fruit drinks and whole milk) are not recommended for frequent consumption due to their energy content and low satiating ability, as energy provided by beverages appears additive to total energy intake. As highlighted in a recent commentary (Allison & Mattes, 2009), additional research addressing the role of beverage consumption in adult weight management is clearly needed.