“Shredding” for Summer? Shift your Focus to Carb Quality not Carb Quantity

With summer approaching, no doubt many Australians are embarking on their yearly ritual to work off the extra weight, commonly known as “shredding” among young men, the group in focus for this month’s edition of GLNC’s Balance. With the abundance of carbophobic messages in the media, the solution for many this year may be to search out and indiscriminately eliminate all or most sources of dietary carbohydrate, including grains (and even legumes).

It’s true! For many young men, one of the first steps towards summer weight loss can be made with carbohydrate foods, but with a focus on making quality choices, not by going extreme and cutting all carbs. 

A key pitfall of the ‘avoid carbs at all costs’ approach to weight management is that it doesn't discriminate between nutrient rich good quality carbohydrate foods (like legumes, whole grain or high fibre grain foods, starchy vegetables, milk and yoghurt) and nutrient-poor discretionary choices such as sweetened beverages, cakes, biscuits, pasties and confectionery. The GLNC 2014 Consumption and Attitudinal Study showed that only one in ten young men are making smart carb choices as often as they should when it comes to grains. In fact, 40% of young men eat less than one serve of whole grain foods a day when they should be having at least three serves.

The study also found that many young men believe grain foods are not an important part of a healthy diet. What they don’t understand is that, by making such poor choices, they are putting themselves at risk of not getting the nutrients they need for health and wellbeing. There is a smarter way to shred.

Smart Shredding – Making good food decisions and limiting discretionary choices

The first question a smart shredder should ask is which foods in your diet are under-performing in terms of nutrition and wellbeing? It is said that we make 200 food decisions a day, and for Australians, particularly young men, recent data suggests that over a third of these food decisions end with discretionary foods choices such as meat pies, muffins, burgers or pizza⁽¹⁾. These foods really are the under performers nutritionally and for health.

The accessibility to processed or takeaway grain foods can make us susceptible to falling into the trap of choosing poorer quality discretionary grain foods over more nutritious core grain food options such as breads, cereals, crispbreads, rice, pasta, noodles or other grains. Not only are discretionary foods such as pastries, pizza, pies and biscuits higher in added saturated fats and salt, they also have very few of the nutrients we need for vitality in the short term and wellbeing in the long term. Research shows that the regular consumption of these ‘discretionary’ foods will increase your risk of obesity and chronic disease such as heart disease, stroke, type 2 diabetes and some forms of cancer⁽²⁾. The first step of a smart shred is to improve overall carbohydrate quality by limiting discretionary choices, those made in preference for core foods.

The second question to ask is which quality carbohydrate foods have a good track record when it comes to nutrition and weight management? In addition to the highest consumption of discretionary grain choices, GLNC’s 2014 Consumption and Attitudinal Study found that only 52% of men meet their whole grain daily target intake⁽³⁾, and only 6.5% of young men reported eating legumes on the day before the last national nutrition survey⁽¹⁾. Given that intake of whole grains, high fibre and low GI grain foods and legumes is linked to better diet quality^(4-6), healthier weight measures and reduced risk of being overweight^{(7, 8)}, it is clear that many young men may be missing out on the benefits of these good quality choices. Whilst it may not be a priority of young men today, the benefits of a healthy eating pattern that includes grain foods and legumes extends beyond “shredding” and has been shown to reduced risk of heart disease, diabetes, bowel cancer and weight gain in the long-term^{(2, 9)}. So whether your goal is shredding for summer, maintaining weight or increasing muscle mass – make choosing grain foods, mostly whole grain or high fibre, and enjoying legumes more often a priority.

A word on portions... The Australian Dietary Guidelines recommend that young men eat at least six serves of core grains, mostly whole grain or high fibre varieties each day as part of a balanced diet.⁽²⁾ The Guidelines are based on the average male doing light physical activity and adopting this recommendation along with serve recommendations for each of the other core food groups (meat and protein foods; vegetables; fruit and dairy). If young men were to achieve these core food recommendations and resist discretionary foods, they would consume on average 2,700 fewer kilojoules per day, which when combined with exercise, could result in satisfactory weight loss.

But what does one serve look like?

• 1 slice of whole grain, wholemeal or high fibre bread
•  ½ a medium wholemeal roll or flatbread (40g)
• 1 wholemeal English muffin or crumpet
• ½ cup cooked brown rice, whole grain couscous, wholemeal pasta or noodles
• ½ cup cooked oats, wheat, barley, rye, bulgur, buckwheat or quinoa
• 2/3 cup (30g) whole grain or high fibre breakfast cereal
• 2 whole grain biscuit breakfast cereals
• ½ cup porridge or ¼ cup muesli
• 3 whole grain or high fibre crispbreads.

The bottom line: Fuel your shred with good quality carbohydrates

In support of the Australian Dietary Guidelines, GLNC encourages all Australians to limit discretionary choices, enjoy grain foods 3-4 times each day, choosing at least half as whole grain or high fibre, and aim to eat legumes at least 2-3 times each week. As it appears most young men are not meeting these guidelines, adopting these healthy habits should be a cornerstone of any plan to achieve and maintain a healthy weight – even a smart “summer shred”.

To make good quality carbohydrate grain and legumes foods the first thing you reach for, stock your pantry with whole grain or high fibre grain foods including bread, breakfast cereal, oats, brown rice, whole grain crispbreads and tinned legumes. When you feel like a snack, rather than choosing an under-performing discretionary choice, reach for whole meal toast or whole grain crispbreads topped with some protein, like cheese or boiled egg.  Finally, skip the bar food and man the kitchen, with GLNC’s simple nutrient-packed recipes that will be sure to keep you on track as the countdown to summer begins.

Head toward a healthy new year

Does the cut all carbs approach sound familiar? This ‘solution’ is not new, for many it was probably the solution (or resolution) last year too and maybe even the year before. While low or no carb crash diets may achieve short term results (if you stick to them), they are also often the basis of the ‘yo-yo diet cycle’ that many people get stuck in for years without achieving AND maintaining their weight related goals.

This year aim to take a longer term view and make your (or help to make your friends, family or clients) goal a “smart and sustained shred” to achieve AND maintain a healthy weight without comprising adequate fibre, nutrient intakes and wellbeing. This approach is consistent with evidenced based recommendations that encourage a focus on carbohydrate food “quality” rather than “quantity” for a healthy weight and reduced risk of weight gain in the long-term ^(10-12).

References

1.            ABS. Australian Health Survey: Nutrition First Results - Foods and Nutrients, 2011-12. Australian Bureau of Statistics, 2014.

2.            NHMRC. Australian Dietary Guidelines Providing the scientific evidence for healthier Australian diets. 2013 Accessed online January 2014.

3.            GLNC. 2014 New Zealand Grains and Legumes Consumption and Attitudinal Report. Unpublished 2015.

4.            Mann KD, Pearce MS, McKevith B, Thielecke F, Seal CJ. Whole grain intake and its association with intakes of other foods, nutrients and markers of health in the National Diet and Nutrition Survey rolling programme 2008–11. British Journal of Nutrition. 2015;113(10):1595-602.

5.            O'Neil CE, Nicklas TA, Zanovec M, Cho S. Whole-grain consumption is associated with diet quality and nutrient intake in adults: the National Health and Nutrition Examination Survey, 1999-2004. Journal of the American Dietetic Association. 2010;110(10):1461-8.

6.            Flood VR, J. Legume consumption and relationship to health outcomes. In: Wollongong Uo, editor. Unpublished.

7.            Williams PG, Grafenauer SJ, O'Shea JE. Cereal grains, legumes, and weight management: a comprehensive review of the scientific evidence. Nutrition reviews. 2008;66(4):171-82.

8.            Mozaffarian D, Hao T, Rimm EB, Willett WC, Hu FB. Changes in Diet and Lifestyle and Long-Term Weight Gain in Women and Men. New England Journal of Medicine. 2011;364(25):2392-404.

9.            Griffiths T. Towards an Australian ‘daily target intake’ for wholegrains. Food Australia. 2007.

10.          Fogelholm M, Anderssen S, Gunnarsdottir I, Lahti-Koski M. Dietary macronutrients and food consumption as determinants of long-term weight change in adult populations: a systematic literature review. Food & nutrition research. 2012;56.

11.          Naude CE, Schoonees A, Senekal M, Young T, Garner P, Volmink J. Low Carbohydrate versus Isoenergetic Balanced Diets for Reducing Weight and Cardiovascular Risk: A Systematic Review and Meta-Analysis. PloS one. 2014;9(7):e100652.

12.          Santiago S, Zazpe I, Bes-Rastrollo M, Sanchez-Tainta A, Sayon-Orea C, de la Fuente-Arrillaga C, et al. Carbohydrate quality, weight change and incident obesity in a Mediterranean cohort: the SUN Project. European journal of clinical nutrition. 2015;69(3):297-302.

The Truth Behind the Paleo Diet

Unless you have been living in a cave you would have heard about the Palaeolithic (Paleo) diet – a diet intended to reflect the eating habits of our hunter-gatherer ancestors who lived between 2.5 million and 10,000 years ago. While the science demonstrates that Paleo diets varied widely based on geographic location and food availability, the key principles of ‘modern day' Paleo diets are to enjoy an abundance of meat, other animal proteins, most fruit, most vegetables (but starchy vegetables like potatoes are restricted by some Paleo dieters), nuts and seeds, along with the strict avoidance of grains, legumes and dairy. Here we review the science presented in a recent meta-analysis on the short term effect of Paleo diet and also, while we are at it explore whether the assumptions that underpin these principles stack up.  

A look at the latest science:

Given the ongoing recent public interest in the Paleo diet, it is not surprising researchers are increasingly studying the healthfulness of this diet. One such study was a recent meta-analysis of randomised control trials (RCT) in which the authors concluded that based on data from the four included studies, there was moderate quality evidence to suggest that the Paleo diet may improve short term (2 weeks to 6 months) markers of metabolic syndrome (i.e. glucose tolerance, triglycerides, blood pressure) to a greater extent than other evidence based dietary interventions. While the headlines in the media covering this paper didn’t hold back and the findings made a splash, the authors cautioned that more evidence is needed before any changes to current guidelines can be made. Here is a snapshot of each study:

The first study was a 12-week RCT of 38 men with heart disease randomly assigned to the Paleo diet. Of the 29 who completed the study the researchers found greater improvements in glucose tolerance compared to those on a Mediterranean-styled diet⁽¹⁾. In the second study, a 6 month RCT, 17 adults with type 2 diabetes patients were randomly assigned to eat a Paleo diet or a standard ‘diabetes diet’. Of the 13 people whose data was included in the analysis, greater improvements in HbA1c (a measure of glucose control), cardiovascular disease risk factors and weight were seen in individuals consuming the Paleo diet⁽²⁾. Whilst the findings of these two RCTs are favourable for the Paleo diet, a limitation of any comparisons that can be drawn is that participants were not limited in the amount of food and energy they consumed. As a consequence individuals on the Paleo diet in the first study actually consumed 25% less kilojoules than the control (Mediterranean) diet over 3 months (Lindberg et al.) and 16% less (Jonsson et al.) than the control diet over 6 months in the second study. As energy intake is a predictor of weight gain or loss and also influences risk factors for disease it is not surprising the diet where people consumed fewer kilojoules led to greater improvements in weight and markers of disease.

In the third two-week RCT, 34 individuals with metabolic syndrome were randomised to the Paleo diet group or an energy matched reference diet based on the Dutch Health Council guidelines. Interestingly, despite this being a randomised controlled trial the baseline characteristics of people assigned to each group differed significantly (a risk with small sample size) and people in the Paleo diet group had significantly higher body weights, BMI’s, ‘characteristics of metabolic syndrome’, TG:HDL-c, lower HDL-c levels (good cholesterol), higher CRP (marker of inflammation) as well as borderline significantly higher waist circumferences. Essentially the Paleo group appears to have been less healthy at baseline. After an energy matched two week intervention the Paleo diet group experienced greater benefits including lower blood pressure, total cholesterol, triglycerides and higher HDL cholesterol⁽³⁾. Given the differences being the groups at baseline, the direct comparison of diets is limited as the improvement in health may have been confounded by the baseline health status of participants.

The final study was a two year RCT including 70 obese post-menopausal women assigned to either a Paleo diet or diet based on Nordic Nutrition Recommendations. Despite losing twenty-one women at follow-up, the authors reported a significant decrease for both groups in total fat mass and waist circumference at 6 months and 24 months. Whilst there was a significantly more pronounced fat loss in the Paleo group at 6 months, this was not significant at 24 months. Triglyceride levels decreased significantly more at 6 and 24 months in the Paleo group versus the control. Changes in all other markers including blood glucose, blood pressure, heart rate, CRP and blood cholesterol were not significantly different between diet groups.

Closer inspection of this study finds that despite regular information and food preparation sessions, participants in the Paleo group struggled to adhere to the assigned protein target (30% of energy intake) assessed via Nitrogen excretion in the urine. This raises the question of the practicality and sustainability of a Paleo-styled diet in the long term. Furthermore in the control group, while they were encouraged to enjoy a diet based on Nordic Nutrition Recommendations the average fibre intakes did not meet the adequate intake of 25g for women, and actually dropped slightly from baseline. This raises the question whether the food choices in the control group reflected a balanced diet with higher fibre choices as encouraged by the Nordic Nutrition Recommendations⁽⁴⁾.

Given the few studies and limitations outlined above, it is not surprising the authors of the recent meta-analysis concluded that further studies are needed to evaluate the short term effect of the Paleo diet. Additionally, this meta-analysis did not evaluate the long term effects of Paleo diets, which are largely unknown. On the other hand, the totality of the scientific research, including evidence from some of the healthiest populations around the world (blue zones), supports the consumption of higher intakes of whole grains, high fibre grain foods and legumes for health and longevity across the lifespan^(5-7). In addition to this there is actually observational evidence in humans to suggest long term lower carbohydrate intake (which may be achieved following a Paleo Diet) may actually increase your risk of early death⁽⁸⁾.

The science behind the paleo story

So despite the lack of scientific evidence to support changes to dietary recommendations (in the short term and certainly not in the long term) in favour of a lower carb Paleo lifestyle, why are there more people than ever suggesting we should all “gopaleo” or “#primal”? The answer to this question is the Paleo story which has thrust this diet into the public’s attention, through an appealing and compelling narrative that tells the nostalgic story of returning to health through eating like our hunter-gatherer ancestors. The strict avoidance of grains and legumes is weaved into this story using three central assumptions. These are three assumption which are disputed by the science.

The first assumption is simply that Palaeolithic people did not consume grains and legumes. This assumption has been contradicted by an Italian team of archaeologists and researchers who recently unearthed stone tools used by humans over 30,000 years ago to grind wild oats into flour⁽⁹⁾. Even more tellingly, studies of human fossils have found remains of grains and legumes on the teeth of Paleo humans⁽¹⁰⁾.

The second assumption of the Paleo diet is that the human body is not genetically adapted to eat plant foods rich in starch like grains and legumes. Once again, a recent review has discredited this assumption. The preparation and cooking of ancient carbohydrate/starch rich foods is thought to have prompted the origin of genes in our mouths which secrete enzymes involved in the breakdown of dietary carbohydrate into glucose. Since glucose is the preferred source of fuel for the brain, experts have suggested that the consumption of carbohydrate by our ancestors would have been critical in the development of the human brain⁽¹¹⁾. Therefore, contrary to the Paleo story’s assumption, the evidence suggests that humans have in fact evolved to consume foods carbohydrate foods such as grains, legumes and other starchy fibre and nutrient rich plant foods.

The third assumption is that because of assumptions one and two, grains and legumes must be unhealthy for humans and contribute to modern day chronic diseases. This is contradicted by the review of the evidence which underpins the Australian Dietary Guidelines that supports the nutritional and health of enjoying a variety of grain foods, mostly whole grain or high fibre grain foods, and legumes⁽⁶⁾. The scientific evidence indicates that people who eat more whole grain or high fibre grain foods and legumes are less likely to be overweight and have a lower risk of developing chronic diseases, including heart disease, type 2 diabetes and certain cancers^(12-16). In fact a recent comprehensive review of 304 meta-analyses and systematic reviews has even shown that whole grain or high fibre grain foods offer the greatest protection against diet related disease, over any other core food group⁽¹⁷⁾.

The Bottom Line

When all the current evidence is considered the story behind the ‘Paleo diet’ just doesn’t stack up.

There are a very small number of studies, all with limitations, that indicate a potential short-term benefit of the paleo diet. Watch this space, as more studies may emerge. In the meantime we need to remember that there are a large number of studies that show the benefits of including quality grains and legumes in the diet. So at this point it appears the positives of keeping grains in far outweigh those of eliminating them.

Like any energy restricted weight loss diet, a Paleo diet which restricts energy intake is likely to result in weight loss and as a result, favourable health measures in the short term. There is however concern that individuals following the Paleo diet may be at risk of falling short of obtaining important nutrients and fibres from whole grains, high fibre grain foods and legumes which may have a negative impact on chronic disease risk over the lifespan^{(6, 18-23)}.

References

1.            Lindeberg S, Jonsson T, Granfeldt Y, Borgstrand E, Soffman J, Sjostrom K, et al. A Palaeolithic diet improves glucose tolerance more than a Mediterranean-like diet in individuals with ischaemic heart disease. Diabetologia. 2007;50(9):1795-807.

2.            Jonsson T, Granfeldt Y, Ahren B, Branell UC, Palsson G, Hansson A, et al. Beneficial effects of a Paleolithic diet on cardiovascular risk factors in type 2 diabetes: a randomized cross-over pilot study. Cardiovasc Diabetol. 2009;8:35.

3.            Boers I, Muskiet FA, Berkelaar E, Schut E, Penders R, Hoenderdos K, et al. Favourable effects of consuming a Palaeolithic-type diet on characteristics of the metabolic syndrome: a randomized controlled pilot-study. Lipids in health and disease. 2014;13:160.

4.            Mellberg C, Sandberg S, Ryberg M, Eriksson M, Brage S, Larsson C, et al. Long-term effects of a Palaeolithic-type diet in obese postmenopausal women: a 2-year randomized trial. European journal of clinical nutrition. 2014;68(3):350-7.

5.            Kim Y, Je Y. Dietary Fiber Intake and Total Mortality: A Meta-Analysis of Prospective Cohort Studies. American journal of epidemiology. 2014;180(6):565-73.

6.            NHMRC. Australian Dietary Guidelines Providing the scientific evidence for healthier Australian diets. 2013 Accessed online January 2014.

7.            Blue Zones  [cited 2015 March ]. Available from: http://www.bluezones.com/.

8.            Noto H, Goto A, Tsujimoto T, Noda M. Low-Carbohydrate Diets and All-Cause Mortality: A Systematic Review and Meta-Analysis of Observational Studies. PloS one. 2013;8(1):e55030.

9.            Mariotti Lippi M, Foggi B, Aranguren B, Ronchitelli A, Revedin A. Multistep food plant processing at Grotta Paglicci (Southern Italy) around 32,600 cal B.P. Proceedings of the National Academy of Sciences. 2015.

10.          Henry AG, Brooks AS, Piperno DR. Microfossils in calculus demonstrate consumption of plants and cooked foods in Neanderthal diets (Shanidar III, Iraq; Spy I and II, Belgium). Proceedings of the National Academy of Sciences. 2011;108(2):486-91.

11.          Hardy K, Brand-Miller J, Brown KD, Thomas MG, Copeland L. The Importance of Dietary Carbohydrate in Human Evolution. The Quarterly Review of Biology. 2015;90(3):251-68.

12.          Williams PG, Grafenauer SJ, O'Shea JE. Cereal grains, legumes, and weight management: a comprehensive review of the scientific evidence. Nutrition reviews. 2008;66(4):171-82.

13.          Du H, van der A DL, Boshuizen HC, Forouhi NG, Wareham NJ, Halkjær J, et al. Dietary fiber and subsequent changes in body weight and waist circumference in European men and women. The American journal of clinical nutrition. 2010;91(2):329-36.

14.          Priebe MG, van Binsbergen JJ, de Vos R, Vonk RJ. Whole grain foods for the prevention of type 2 diabetes mellitus. The Cochrane database of systematic reviews. 2008(1):Cd006061.

15.          Jacobs DR, Jr., Marquart L, Slavin J, Kushi LH. Whole-grain intake and cancer: an expanded review and meta-analysis. Nutrition and cancer. 1998;30(2):85-96.

16.          Kushi LH, Meyer KA, Jacobs DR, Jr. Cereals, legumes, and chronic disease risk reduction: evidence from epidemiologic studies. The American journal of clinical nutrition. 1999;70(3 Suppl):451s-8s.

17.          Fardet A, Boirie Y. Associations between food and beverage groups and major diet-related chronic diseases: an exhaustive review of pooled/meta-analyses and systematic reviews. Nutrition reviews. 2014:n/a-n/a.

18.          Mellen PB, Walsh TF, Herrington DM. Whole grain intake and cardiovascular disease: a meta-analysis. Nutrition, metabolism, and cardiovascular diseases : NMCD. 2008;18(4):283-90.

19.          Pereira MA, O'Reilly E, Augustsson K, Fraser GE, Goldbourt U, Heitmann BL, et al. Dietary fiber and risk of coronary heart disease: a pooled analysis of cohort studies. Arch Intern Med. 2004;164(4):370-6.

20.          Bazzano LA, Thompson AM, Tees MT, Nguyen CH, Winham DM. Non-soy legume consumption lowers cholesterol levels: A meta-analysis of randomized controlled trials. Nutrition, metabolism, and cardiovascular diseases : NMCD. 2011;21(2):94-103.

21.          Jayalath VH, de Souza RJ, Sievenpiper JL, Ha V, Chiavaroli L, Mirrahimi A, et al. Effect of Dietary Pulses on Blood Pressure: A Systematic Review and Meta-analysis of Controlled Feeding Trials. American Journal of Hypertension. 2014;27(1):56-64.

22.          Ha V, Sievenpiper JL, de Souza RJ, Jayalath VH, Mirrahimi A, Agarwal A, et al. Effect of dietary pulse intake on established therapeutic lipid targets for cardiovascular risk reduction: a systematic review and meta-analysis of randomized controlled trials. Canadian Medical Association journal. 2014.

23.          Aune D, Norat T, Romundstad P, Vatten LJ. Whole grain and refined grain consumption and the risk of type 2 diabetes: a systematic review and dose-response meta-analysis of cohort studies. European journal of epidemiology. 2013;28(11):845-58.