One commonly heard propositions to combat the obesity epidemic is to tax soft drinks. No doubt, sugary soft drinks are a common and important source of “empty” calories, but will taxing soft drinks really reduce obesity rates?

This assumption was now examined by Yale University’s Jason Fletcher and colleagues, in a paper just published in Contemporary Economic Policy.

The researchers collected information on taxation of soft drinks with respect to specific excise taxes on soft drinks and other snack taxes, general state sales taxes, and special soft drink exceptions to food exemptions from sales taxes in several US States between 1990 to 2006. Height and weight data was used from the representative NHANES III data set.

Using complicated models accounting for a variety of potential confounders, the authors confirmed that state soft drink taxes have a statistically significant impact on behavior and weight; however, the magnitude of the effect is surprisingly small.

Thus, a 1% increase in the state soft drink tax rate leads to a decrease in BMI of 0.003 points and a decrease in obesity and overweight of 0.01 and 0.02 %, respectively.

There were also significant differences on how soft drink taxes affect different demographic groups. For e.g. a 1% increase in the soft drink tax rate decreases BMI by over 0.01 points for the lowest three categories (income below $20,000) and nearly 0.01 points for the highest category (income above $50,000).

In addition, The impact of state soft drink taxes is larger for females, middle-aged and older individuals, individuals with greater education, and varies according to race and ethnic categories.

The authors point out that soft drink consumption represents only 7% of the total energy intake and one should therefore expect only modest changes in population weight through soft drink consumption responses to small tax increases.

In fact, they estimate that even a 20% increase in soft-drink taxes would only lead to a mean BMI change of 0.06 points, although the impact may be somewhat larger for some demographic groups.

Indeed, even if soft drinks were to be taxed at around 58%, the current average taxation rate for cigarettes,
the researchers estimate that mean BMI in the United States would likely only decrease by 0.16 points and reduce the proportion of overweight or obesity in the population by 0.7%.

In comparison, the between 1990 and 2006, the average increase in population BMI in the US was around 2.3 points.

While the authors conclude that although the effect of increased taxation of soft drink may do little for obesity, they point out that there may be other health benefits, including improvement in dental health.

Additionally, an increase in the soft drink tax of this size would raise considerable revenue for the federal and state governments that could perhaps be used to implement other measure to address the obesity epidemic.

While the authors by no means wish to condone the increased consumption of soft drinks, their analysis clearly suggests that any hope that simply slapping a tax onto soft drinks will somehow reduce obesity rates appears unfounded.

AMS
Edmonton, Alberta

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Fletcher JM, Frisvold D, & Tefft N (2010). Can Soft Drink Taxes Reduce Population Weight? Contemporary economic policy, 28 (1), 23-35 PMID: 20657817

There is little doubt that changes in diet and physical activity can seriously reduce risk for cardiovascular disease (and countless other conditions from arthritis to cancer).

But changing diet and activity levels both at individual and population levels remains a major challenge. Not that these changes are not possible (they are), but rather that practitioners don’t know where to start and often default to well-meaning but useless advise (eat less - move more).

Last week, the American Heart Association (AHA) Prevention Committee of the Council on Cardiovascular Nursing released a comprehensive collation of the current evidence regarding interventions to promote physical activity and dietary lifestyle changes for cardiovascular risk factor reduction in adults.

Although the document does not specifically address weight management, the principles and learnings from this document certainly apply as much to managing excess weight as they do to dealing with other chronic conditions like hypertension, dyslipidemia or diabetes.

The following intervention strategies and principles meet the highest levels of evidence (Level A or B):

Cognitive-behavioral strategies for promoting behavior change:

• Design interventions to target dietary and PA behaviors with specific, proximal goals/goal setting (Level of evidence: A)

• Provide feedback on progress toward goals. (Level of evidence: A)

• Provide strategies for self-monitoring. (Level of evidence: A)

• Establish a plan for frequency and duration of follow-up contacts (eg, in-person, oral, written, electronic) in accordance with individual needs to assess and reinforce progress toward goal achievement. (Level ofevidence: A)

• Utilize motivational interviewing strategies, particularly when an individual is resistant or ambivalent about dietary and PA behavior change. (Level of evidence: A)

• Provide for direct or peer-based long-term support and follow-up, such as referral to ongoing community-based programs, to offset the common occurrence of declining adherence that typically begins at 4–6 months in most behavior change programs. (Level of evidence: B)

• Incorporate strategies to build self-efficacy into the intervention. (Level of evidence: A)

• Use a combination of the above strategies (eg, goal setting, feedback, self-monitoring, follow-up, motivational interviewing, self-efficacy) in an intervention. (Level of evidence: A)

• Use incentives, modeling, and problem solving strategies. (Level of evidence: B)

Intervention processes and/or delivery strategies:

• Use individual- or group-based strategies. (Level of evidence: A)

• Use individual-oriented sessions to assess where the individual is in relation to behavior change, to jointly identify the goals for risk reduction or improved cardiovascular health, and to develop a personalized plan to achieve it. (Level of evidence: A)

• Use group sessions with cognitive-behavioral strategies to teach skills to modify the diet and develop a PA program, to provide role modeling and positive observational learning, and to maximize the benefits of peer support and group problem solving. (Level of evidence: A)

• For appropriate target populations, use Internet- and computer-based programs to target dietary and PA change; evidence is less for targeting PA alone; adding a form of E-counseling improves outcomes. (Level of evidence: B)

• Use individualized rather than nonindividualized print- or media-only delivery strategies. (Level of evidence: A)

Addressing cultural and social context variables that influence behavioral change:

• Utilize church, community, work, or clinic settings for delivery of interventions. (Level of evidence: B)

• Use a multiple-component delivery strategy that includes a group component rather than individual-only or group-only approaches. (Level of evidence: A)

• Use culturally adapted strategies, including use of peer or lay health advisors to increase trust; tailor health messages and counseling strategies to be sensitive to the cultural beliefs, values, language, literacy, and customs of the target population. (Level of evidence: A)

• Use problem solving to address barriers to PA and dietary change, such as lack of access to affordable healthier foods, lack of resources for PA, transportation barriers, and poor local safety. (Level of evidence: B)
• Nothing revolutionary here or in fact very different from the way most evidence-based weight management programs already work (scams excluded). In fact this list of recommendations provides a valuable checklist to make sure your program is hitting all the relevant buttons

Good to know that there is actually strong scientific evidence to support most of what we do at WeightWise.

AMS
Edmonton, Alberta

Hat tip to Sebely for pointing me to this article

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Artinian NT, Fletcher GF, Mozaffarian D, Kris-Etherton P, Van Horn L, Lichtenstein AH, Kumanyika S, Kraus WE, Fleg JL, Redeker NS, Meininger JC, Banks J, Stuart-Shor EM, Fletcher BJ, Miller TD, Hughes S, Braun LT, Kopin LA, Berra K, Hayman LL, Ewing LJ, Ades PA, Durstine JL, Houston-Miller N, Burke LE, & on behalf of the American Heart Association Prevention Committee of the Council on Cardiovascular Nursing (2010). Interventions to Promote Physical Activity and Dietary Lifestyle Changes for Cardiovascular Risk Factor Reduction in Adults. A Scientific Statement From the American Heart Association. Circulation PMID: 20625115

I am currently in Oslo for the 20th European Meeting of the European Society of Hypertension. Some of my readers may recall that 25 years ago, I started my research career with studies on the effects of salt on blood pressure - the debate on salt reduction was not new then - the debate is still alive today.

The question is not whether or not increased salt intake can increase blood pressure in some people - indeed, it does and much of my work at the time focused on trying to understand the physiology and genetics of this phenomenon.

Proponents of sodium restriction point to the number of heart attacks and strokes that could theoretically be prevented if population-wide salt reduction did indeed translate into lower blood pressure for the population, but to this date, this has yet to be shown in a prospective randomized-controlled trial proving that eating less salt actually saves lives.

Critics of these proposals fear that reducing the salt intake of the population may have unintended consequences for some.

A new spin on this theory of unintended consequences now comes from a paper by John Hayes and colleagues from Pennsylvania State University, published in the latest edition of Physiology and Behavior.

Hayes and colleagues examined the response of so-called “bitter supertasters” to varying amounts of salt in a wide range of foods. These bitter supertasters make up about 25% of the population and are genetically hypersensitive to bitter tastes, leading them to naturally avoid some vegetables and other foods that taste naturally bitter.

The researchers assessed the liking and intake of foods with varying amount of saltiness among 87 healthy adults (45 men).

Supertasters reported greater saltiness in chips/pretzels and broth at levels comparable to regular-sodium products; greater sensory and/or liking changes to growing sodium concentration in cheeses (where sodium ions mask bitterness) and broths; and less frequently salting foods.

Increased propensity for bitter supertasting, independently explained variability in consuming high-sodium foods by impacting salt sensation and/or liking.

Bitter-supertasters reported greater changes in sensation when more salt was added to broth, which then associated with greater changes in broth liking, and with more frequent high-sodium food intake.

In contrast, greater papillae number was associated with less frequent high-sodium food intake via reduced liking for high-fat/high-sodium foods.

The researchers conclude that, variation in sensations from salt is associated with differences in hedonic responses to high-sodium foods and thus sodium intake between bitter-supertasters and non-supertasters.

Despite adding less salt, bitter supertasters consumed more sodium through food, as salt was more important to preference, both for its salty taste and masking of bitterness.

The researchers suggest that bitter-supertasters may use increased salt to mask bitterness in naturally bitter foods including vegetables and other foods that may be deemed to be healthy.

Reducing salt intake may make these foods less appealing to supertasters and may therefore adversely affect their nutrient intake.

Whether or not this is in fact true, it does appear that some people may have a natural (genetic) preference for higher salt in their diets - and may respond to population wide restrictions in salt use by simply reaching for the shaker.

AMS
Oslo, Norway

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Hayes JE, Sullivan BS, & Duffy VB (2010). Explaining variability in sodium intake through oral sensory phenotype, salt sensation and liking. Physiology & behavior, 100 (4), 369-80 PMID: 20380843

Fenugreek (Trigonella foenum-graecum), referred to in Hindi as Methi, is a common ingredient in South Asian cuisine. Its seeds are an essential component of curry powder - its leaves are eaten as a vegetable.

Traditional Indian medicine has long attributed medicinal properties to fenugreek, especially for the treatment of diabetes.

Now, Taku Uemura and colleagues from Kyoto University in Japan publish findings showing that the beneficial effects of fenugreek may derive from its capacity to stimulate formation of new fat cells and reduce inflammation in fat tissue.

In this paper, published online in Molecular Nutrition and Food Research, Uemura and colleagues studied the effects of fenugreek extract on adipocyte size and inflammation in adipose tissues in diabetic obese mice and identified diosgenin as the active substance in fenugreek.

Treatment of diabetic mice with a high fat diet supplemented with 2% fenugreek not only reduced diabetes, it also reduced the size of adipocytes while promoting formation of new (smaller and healthier) fat cells.

Fenugreek also reduced infiltration of macrophages (white blood cells) into adipose tissues and decreased the expression of pro-inflammatory genes.

I have previously blogged on the putative beneficial metabolic effects of tumeric, the yellow spice that gives curry powder its colour. Interestingly in that study, tumeric was found to prevent the formation of fat cells and promote adipocyte cell death - in some ways the exact opposite of what fenugreek appears to do.

Perhaps it is this complex action of these spices, that may in part cancel out rather can complement their beneficial effects.

In any case, it probably remains to be explained why, despite the avid and regular ingestion of these anti-diabetic spices on the Indian subcontinent, it is now home to the greatest number of people with type 2 diabetes anywhere in the world.

AMS
Edmonton, Alberta

Uemura T, Hirai S, Mizoguchi N, Goto T, Lee JY, Taketani K, Nakano Y, Shono J, Hoshino S, Tsuge N, Narukami T, Takahashi N, & Kawada T (2010). Diosgenin present in fenugreek improves glucose metabolism by promoting adipocyte differentiation and inhibiting inflammation in adipose tissues. Molecular nutrition & food research PMID: 20540147

It is estimated that at any given time, as many as a third of people with overweight and obesity are on a restrictive diet (in addition to an unknown number of normal weight people, who follow diets in the hope that they are healthier and may prevent weight gain).

As most of the popular diets consist of restricting overall caloric intake (despite often misleading claims to the contrary) and amounts of certain foods, the question arises whether or not there may be any potential drawbacks to being on such diets.

This question is of particular importance as many people with overweight and obesity often have nutrient deficiencies to start with - a situation that can potentially become worse as total food consumption decreases.

In a paper published online in the Journal of the International Society of Sports Nutrition, Jayson Calton, from North Venice, FL, who holds a PhD in holistic medicine, examines the potential of micronutrient deficiencies with popular diet plans.

Micronutrients include vitamins and minerals, crucial nutrients that are required in very low concentrations but are essential for maintaining proper health.

Calton analysed suggested daily menus from four popular diet plans (Atkins for Life diet, The South Beach Diet, the DASH diet, The Best Life Diet) to determine if they met the USDA recommended dietary intake (RDI) for 27 micronutrients.

According to Calton’s analysis, none of these four popular diet plans provided minimum RDI sufficiency for all 27 micronutrients analyzed.

In fact, the four diet plans, which provided an average daily caloric intake of around 1750 KCal/day, were found to be RDI sufficient in only 12% of the 27 micronutrients examined.

Further analysis of the four diets found that an average calorie intake of 27,000 calories of these diet would be needed to achieve sufficiency in all 27 micronutrients.

Six micronutrients (vitamin B7, vitamin D, vitamin E, chromium, iodine and molybdenum) were identified as consistently low or nonexistent in all four diet plans.

When these six micronutrients were removed from the sufficiency requirement one would still have to eat an about 3500 calories of these diets every day to reach 100% sufficiency in the remaining 21 micronutrients.

As Calton concludes:

“These findings are significant and indicate that an individual following a popular diet plan as suggested, with food alone, has a high likelihood of becoming micronutrient deficient“

It may thus be not such a bad thing that the vast majority of people fail to stick with such diets over any significant periods of time after all.

Those who do, may likely benefit from taking additional micronutrient supplements while on these diets.

AMS
Edmonton, Alberta

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Calton JB (2010). Prevalence of micronutrient deficiency in popular diet plans. Journal of the International Society of Sports Nutrition, 7 (1) PMID: 20537171