Dietary proteins have been shown to be more effective at prolonging satiety and suppressing food intake than carbohydrates and fats. However, different dietary proteins appear to vary in their ability to influence satiety and reduce food intake.

This is nicely demonstrated in a new study by Sebely Pal and Vanessa Ellis from the University of Curtin, Perth, Australia, published in the British Journal of Nutrition.

Pal and Ellis studied 22 healthy male normal-weight volunteers, who were studied on four separate occasions in a randomised, single blind, cross-over design study. On each occasion the subjects were given a liquid test meal, containing either tuna, turkey, whey or egg albumin, administered as a chocolate-flavoured shake.

Whey protein resulted in a significantly lower blood glucose and significantly higher insulin response than the same amount of tuna, egg, or turkey protein. Similarly, subjects rated their level of hunger as lower after the whey protein compared to the other proteins.

Most importantly perhaps, mean energy intake at an ad libitum meal four hours after the test meal was around 100 KCal lower with the whey meal than with the tuna, egg and turkey meals.

The authors speculate that this satiating effect of whey proteins may be related to the fact that whey protein has a faster rate of digestion and absorption than other proteins, producing a rapid peak in plasma amino acids which may contribute to their effect on satiety. Whey proteins also have one of the highest concentrations of branched-chain amino acids (BCAA) compared to other protein sources, which, in turn, may affect release of enteral hormones or insulin.

Interestingly, insulin, apart from its well-known actions on glucose and lipid metabolism, is also thought to be a satiety hormone, with increased insulin levels in the brain eliciting a net catabolic response influencing food intake regulatory mechanisms

Although these findings suggest a potential for hunger suppression and weight loss in overweight or obese individuals, it would be important to show that there is no compensatory effect in caloric intake that may develop over time as subjects go into negative energy balance over time.

Such an effect would ultimately defend body weight and prevent long-term weight loss.

Nevertheless, the study supports the notion that at least in the acute setting, all proteins may not be equal in their ability to satiate and decrease hunger.

AMS
Denver, CO

You can now also follow me and post your comments on Facebook

Pal S, & Ellis V (2010). The acute effects of four protein meals on insulin, glucose, appetite and energy intake in lean men. The British journal of nutrition, 1-8 PMID: 20456814

The key to long-term success with bariatric surgery is certainly life-long dietary modification.

While most guidelines focus on the immediate needs of patients undergoing bariatric surgery, long term nutrition continues to be an important issue, even in weight-stable patients.

As people with bariatric surgery tend to eat far fewer calories than before and (depending on the type of surgery) may be more prone to certain deficiencies, a “balanced” diet for them will look very different from that recommended for the general population.

This issue is now addressed in a paper by Violeta Moize from the University of Barcelona, Spain, just published in OBESITY SURGERY.

Based on the current knowledge of dietary strategies and behaviors associated with beneficial long-term nutritional outcomes in post-bariatric surgery patients, the researchers have developed a “bariatric food pyramid”, that can be used as a teaching tool and reminder to patients.

Given the nature of the operation and the physiological demands of this very special patient population, it is not surprising that there is a strong focus on high-quality protein, balanced with nutrient-dense complex carbohydrates and healthy sources of essential fatty acids.

Hopefully this tool will help both therapists and patients better understand nutrition recommendations for a healthy long-term post-op diet.

AMS
Station Touristique Duchesnay, Quebec

You can now also follow me and post your comments on Facebook

Moizé VL, Pi-Sunyer X, Mochari H, & Vidal J (2010). Nutritional Pyramid for Post-gastric Bypass Patients. Obesity surgery, 20 (8), 1133-41 PMID: 20401543

After yesterday’s post on the potential benefits of eating blueberries, some readers noted that one should not discount the calories in fruit. In addition, there appears to be a “myth” out there that because of the sugar in fruit, they should be considered a high-glycemic food and could therefore be counterproductive in weight-loss diets - especially for people trying a “low-carb” approach to weight loss.

On the other hand, dietary guidelines regularly recommend more fruit and vegetables as part of a healthy balanced diet.

So does eating fruit sabotage efforts to lose weight?

This question was addressed by Kerstin Schroder from the University of Utah in a study just published in Nutrition.

Schroder examined the effect of fruit consumption on body weight and weight loss in 77 overweight and obese dieters enrolled in a 6-month randomized controlled trial testing the effects of a computer-assisted dieting intervention program with the goal to decrease energy intake, increase fruit and vegetable consumption, and maintain a balanced diet.

Overall weight loss during the intervention was rather modest (average weight loss of 3.23 lb).

Although vegetable consumption increased as a result of the intervention, fruit consumption did not.

However, after controlling for age, gender, physical activity, and daily macronutrient intake, higher fruit consumption was associated with a lower BMI both at the baseline and the end of the study.

Although overall fruit consumption did not increase, those participants, who did increase fruit consumption, lost more weight. Indeed, difference scores in fruit consumption (which varied from −1.50 to +2.86 servings per day) turned out to be the only significant predictor of weight loss among the nutrition variables, with an incremental contribution of 5.0% to 5.1% of the variance explained in weight loss and BMI change scores.

No such relationship was seen with changes in vegetable intake. Thus, increases in vegetable intake explained only 4% incremental variance in weight loss during the first 3 mo of the trial and explained none of the variance in weight loss over the entire 6-mo period.

The results not only suggest that fruit and vegetables may well have different effects on weight control, but also that eating more fruit by no means reduces the likelihood of weight loss.

Obviously, simply adding fruit to your diet is very unlikely to produce weight loss. Moreover, the study does not tell us if all fruit are equal or if different fruit vary in their ability to promote or sustain weight loss.

Certainly there appears nothing about fruit that warrants either damning them for hampering weight loss nor promoting them as “super foods” for achieving a healthy weight (whatever that may be).

They’re simply a healthy food that should be part of any balanced diet.

AMS
Edmonton, Alberta

Click here for additional posts and comments on my FaceBook pag

Hat tip to Sebely for pointing me to this article

Schroder KE (2010). Effects of fruit consumption on body mass index and weight loss in a sample of overweight and obese dieters enrolled in a weight-loss intervention trial. Nutrition (Burbank, Los Angeles County, Calif.), 26 (7-8), 727-34 PMID: 20022464

Eating more fruit and vegetables is a common recommendation in dietary guidelines to prevent everything from obesity and heart disease to premature aging and cancer.

In this context, berries are of particular interest, as they are particularly rich in anti-oxidants and a variety of phytochemicals like polyphenols, anthocyanins, proanthocyanidins, resveratrol, flavonols, and tannins that have demonstrated beneficial effects in vitro and in vivo studies.

But randomised controlled studies on the health effects of eating berries remain scarce.

It is therefore of interest that Arpita Basu and colleagues from Oklahama State University, in a paper just published in the the Journal of Nutrition, now report the results of a randomised controlled trial of blueberries in men and women with obesity and the metabolic syndrome.

In this study, the researchers examined the effects of eight weeks of daily blueberry supplementation (50 g freeze-dried blueberries, approximately 350 g fresh blueberries) compared to equivalent amounts of fluids in 48 participants with an average BMI of around 38 kg/m2).

While blueberries did not appear to have any effect on serum glucose or lipid profiles, there was a significant decrease in systolic and diastolic blood pressures (-6 and -4%, respectively) versus controls (-1.5 and -1.2%).

There was also a roughly 30% decrease in plasma levels of oxidized LDL in the blueberry group compared to a 9% reduction in controls.

No change in weight was reported.

Although this is a short-term study of only eight weeks duration, the data does suggest that there may be beneficial effects of regular consumption of blueberries on cardiovascular risk factors. Whether or not these effects translate into better health outcomes in the long term remains to be seen.

AMS
Edmonton, Alberta

Click here for additional posts and comments on my FaceBook page

Basu A, Du M, Leyva MJ, Sanchez K, Betts NM, Wu M, Aston CE, & Lyons TJ (2010). Blueberries Decrease Cardiovascular Risk Factors in Obese Men and Women with Metabolic Syndrome. The Journal of nutrition PMID: 20660279

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

Click here for additional posts and comments on my FaceBook page

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