Diet Is a Four-Letter Word
Overweight and obesity rates might be leveling off, but as more nations become more developed, waist expansion is spreading worldwide. In fact, the global girth rate appears to be untouched by an equally epidemic and persistent obsession with diets—diets of all kinds and of all claims.
Americans, especially, have never given up chasing diets, generally the same ones with different names. For example, the low-carb diet, originally conceived in the 1800s, has undergone many reincarnations, morphing into The Drinking Man’s Diet in the 60s, the Atkins Diet in the 70s, the South Beach Diet, the Paleo Diet, and now the ketogenic diet.
This presents a serious dilemma for the prospective food provider when addressing the needs of the consumer. What is the best strategy? Follow the ever-changing trend of diet fads and try to anticipate the next fashion, or consider diet for what it is, just another four-letter word? A long overdue shift to a lasting strategy is in order, one that outlives the fads and the soundbite science.
Just such a strategy was suggested in a study published in the Journal of the American Medical Association last February. The study, conducted at Stanford University, weighed in on the continuous and generally contentious debate over which dietary approach to weight loss is best, low fat or low carb.
Known as the “Diet Intervention Examining the Factors Interacting with Treatment Success (DIETFITS)” study, it was a comprehensive, long-term, randomized clinical trial of more than 600 non-diabetic adults aged 18 to 50, with a body mass index between 28 and 40. Subjects were randomly assigned to a healthy 12-month diet that was either low in fat or low in carbohydrates.
The goal was to comprehensively address the numerous dietary studies over the decades that have reported a spectrum of results, with some subjects losing a significant amount of weight, and some losing almost no weight at all, some responding to a low-fat diet, and others responding to a low-carb approach.
At the end of the year, each group averaged a weight loss of about 6kg (13lb.) There was no significant difference between the groups. What did happen in both groups was a natural decrease in caloric intake equaling about 500 calories per day.
In other words, focusing on quality of the diet appeared to act as a natural appetite control that overcame the differences in diet composition. Nothing in the results indicated a genetic response to the different diets.
What appeared to work for weight loss was the simple, old-fashioned “eat less, lose weight” formula. But how does one eat less without the pain of dieting? The message again was simple: Increase the quality of the diet.
Put more succinctly, the results appeared to support the more holistic “better for you” approach of “using better ingredients equals steady weight loss and better weight management,” regardless of exact dietary composition.
There are two ways nutrition researchers describe natural quantity control when it comes to food: satiety and satiation. Satiety describes the tendency to delay eating after a meal. (“I’ve eaten; when do I feel like eating again?”) Satiation describes the satisfying “punch” of food during the meal. (“I’m hungry; when do I feel like I’ve had enough?”)
Both satiety and satiation tend to merge. Higher quality foods that more effectively meet nutrient needs can act as a mechanism for natural quantity control. This introduces nutrient density to the equation—greater nutrition per calorie unit equals natural satiation and satiety.
In studies comparing animal vs. legume protein, the source made no difference in energy consumption.
For weight management product developers, this suggests a simple approach. Provide quality from a variety of sources and be rewarded with consumer loyalty.
Natural satiety can be gauged with the Satiety Index, a measure of the tendency of a food to stave off hunger compared to eating a standard meal of white bread alone.
The satiety champions are slow-cooked complex starches, specifically those from root vegetables and especially potatoes (boiled, of course, not fried). Also high on the satiety scale are foods like slow-cooked whole grains (such as oatmeal) and legumes. These foods can be considered healthy staple carbohydrates.
Protein carries a reputation for being the macronutrient that provides the greatest satiation. The rationale for a diet rich in protein during energy (calorie) restriction is based on two fundamental principles: First, protein helps to maintain muscle integrity during energy restriction, with muscle requiring more energy to maintain. Second, protein has a greater thermic effect of food than either carbohydrate or fat, meaning that the body has to invest more energy to get energy out of protein.
Protein contains nitrogen as part of each subunit. The building blocks of protein are amino acids, and those are converted to energy; however, this requires the removal of nitrogen.
Meeting protein needs has been shown to reduce calorie intake, but going beyond the acceptable macronutrient distribution range of dietary protein intake of 10 to 35% of calories has demonstrated no additional benefit.
In studies comparing beef and pork vs. legume protein, the source of protein made no difference in energy consumption. Other proteins might have different effects. Whey proteins have a high concentration of branched-chain amino acids (BCAA), especially leucine, which is needed for protein synthesis. Some studies suggest that BCAAs support appetite control. Others suggest that milk proteins work best in appetite control as part of the whole food.
Legumes, such as peanuts, soy beans, dry beans, broad beans, peas, chickpeas, and lentils, are not only excellent protein sources, they’re also rich in the type of fibers that bind water and slow the movement of food through the digestive tract. The added effects are to delay the entrance of glucose into the blood and increase nutrient density, both of which contribute to satiety.
Legume flours have become popular as additions to pastas, baked products such as bread, and milk analogs such as almond milk. Milk substitutes from nuts and grains are highly popular, but they typically are low in protein. Legume proteins, such as pea protein and chickpea protein, have become staple ingredients for enhancing the protein content of many of these products. And, of course, one of the biggest categories in which these plant proteins are being applied is vegetarian meat analogs.
The earliest weight-loss diets paid special attention to fiber. “Eat more roughage!” was a call that went back to John Harvey Kellogg, MD, and the Clean Living Movement at the turn of the 20th century. With the current focus on diet for whole health, does fiber matter as much?
The answer is an unqualified “yes.” In fact, functional fibers do more than add low-calorie, high-satiety bulk (which they do, of course). As Kellogg so presciently surmised more than a century ago, the right fibers help balance the microbiome and promote better health through a stronger immune system.
Although Kellogg did not know about inulin, resistant starch, or even the classes of oligosaccharides such as FOS (fructo-oligosaccharides), GOS (galacto-oligosaccharides), and MOS (mannan-oligosaccharides), Kellogg recognized that fiber had a powerful, positive effect on the body. And now it is known that these indigestible fibers produce compounds that feed probiotic bacteria.
It has been well established that imbalances in the gastrointestinal microbiome are a key factor in obesity. The FDA has recognized it as well. While last year food companies using resistant starch received permission to claim on labels that the compound helps to mitigate symptoms of diabetes, just this spring the FDA and USDA reaffirmed that inulin can be labeled as a dietary fiber.
These indigestible fibers also have demonstrated an ability to trigger the production of chemical compounds that beneficially impact hunger and satiety hormones. Inulin and resistant starch also have exhibited a capacity for regulating blood sugar levels and blood lipid levels. And in a recent study, inulin was shown to aid in increased fat oxidation.
All in all, the multiple and synergistic roles dietary fibers play in managing the overall health that leads to better weight and energy make fiber a perfect fit for the new diet paradigm.
Fibers from sources such as high-amylose corn, chicory root, potatoes, green bananas, and chickpeas and other legumes have increased not only in availability but in formulation functionality. Ingredient technologists have developed forms of these fibers with high solubility and clean flavor, plus they actually can be used to improve texture in products where fiber once had a negative impact on final product texture.
Recognition of the value of healthy fats in weight management continues to grow. One ingredient category at the forefront of this new paradigm is that of nuts.
A wealth of epidemiological evidence suggests that the consumption of nuts is associated with healthy weight loss and weight management, even though fat comprises about 80% of the calories of most nuts.
Slowing, but Still Growing
What has been described an obesity epidemic in the US could now be considered a consistent feature, a new normal for Americans. The latest figures from the Centers for Disease Control place the rates of obesity at 36.5% overall for adults. Breaking down the numbers by age suggests something interesting though not surprising.
The obesity rate for Americans aged 20-39 years is 32.5%, while that of middle-aged Americans (40-59 years of age) climbed to 40.2%. Older folks (age 60+) rest at 37% (though not statistically different from that of the middle-aged). In other words, whatever it is about our diet or lifestyle (or both) that promotes obesity accumulates with time.
To be clear, the definition of obesity as opposed to overweight is defined in terms of Body Mass Index (BMI), the most commonly used estimate to screen for overweight and obesity in adults and children. BMI is defined as weight in kilograms divided by height in meters, squared. By this measure, normal BMI is from 18.5 to 24.9. Overweight is from 25 to 29.9, and obesity is 30 and above, with 40+ considered extreme obesity.
For most people, BMI is related to the amount of body fat. However, there are flaws with BMI, the primary one being that it does not consider body composition. It merely assumes that a higher than normal BMI equals higher than normal body fat, based on observations of most individuals. Because muscle weighs more than fat, a very muscular person could be counted as overweight or even obese depending upon his or her physique. The extreme example is that of a body builder with a very low body fat percentage. Even with this flaw, BMI is still considered a useful measure for most people.
There are several mechanisms by which nuts are believed to positively impact body weight. The combination of protein, fat, and some carbohydrate works individually as well as synergistically to increase satiety while demanding more energy expenditure to metabolize. Often nuts are incompletely digested, which reduces their effective caloric impact.
Each nut has its own properties. Almonds are rich in calcium and fiber. In fact, almond skins are marketed as an independent fiber source. Walnuts are a good source of omega-3 fatty acids, rare in many nuts.
Cashews are one of the richest sources of protein in the nut family, and high in oleic acid, the monounsaturated fatty acid that dominates in almonds, hazelnuts (high in fiber), pistachios, and macadamia nuts. Cashews are turned into high-protein milks and non-dairy ice creams.
Seeds tend to be rich in omega-6 fatty acids and generally higher in protein than nuts. Like omega-3 fatty acids, omega-6 are classified as essential. Sunflower seeds are a protein-rich and an under-used potent source of many nutrients. Naturally high in thiamin (unusual in unenriched foods), sunflower seeds and sesame seeds are good sources of minerals. Pumpkin seeds are naturally very high in iron.
Olives and avocados have been recognized sources of healthful fats for years. Olive oil especially, thanks to the Mediterranean Diet popularized by Oldways Preservation Trust, was the primary driver that shifted the national paradigm away from the blanket demonization of fat.
With a similar nutrient profile to olive oil, avocado oil has become a fast-trending ingredient. So, too, have oils from seed sources such as grape seed, flax seed, hemp, and especially chia.
While refined flour products account for a significant portion of the increase in per capita calorie intake, whole-grain cereals make up only a small portion of staple foods. Yet staple grains, including wheat, rice, barley, rye, oats, and millet, have sustained cultures for thousands of years, long before obesity was a problem.
Whole grains have a big role to play in foods marketed for weight management and overall health. The combination of complex carbohydrates, protein, and healthful fats couples nicely with the consumer perception of them as ingredients for active and healthy lifestyles.
Teff, an African grain considered a racing edge by Ethiopian distance runners like Olympic gold medalist Haile Gebrselassie, is rich in protein and minerals. It is one of several so-called ancient grains whose popularity is on the rise. Other grains and pseudo-cereals gaining favor in better-for-you products targeting whole-body health and weight management include amaranth, buckwheat, and quinoa. All these ingredients are good sources of dietary fiber and minerals.
According to the FDA, fewer than 5% of adults in the 19–50 age group consume the recommended servings of whole grains. Recently, manufacturers have been offering more whole-grain products, leading to an increase in both sales and awareness of the value of whole grains. Breads and breakfast cereals amount for over 60% of this increase. Whole-grain pasta use is also on the rise.
Other trends in grain consumption seem to be here to stay. Though the gluten fear has been greatly overblown, one positive outcome is that persons suffering from Celiac disease and in true need of gluten-free foods have a much greater variety of staple carbohydrates to choose from. In truth, only wheat, rye, and barley, along with relatives like triticale, spelt, and kamut contain significant amounts of gluten, a substance composed of two proteins—glutenin and gliadin—that cause serious problems for less than 1% of the population.
Corn has received a great deal of negative press because of high-fructose corn syrup (HFCS), even though that sweetener is virtually identical to sucrose.
There is no support for HFCS having a role in obesity or type 2 diabetes. Corn is also a source of resistant starch (RS), which represents the portion of starch not accessible to the digestive enzymes called amylases. These enzymes normally break starch into its glucose components so that they can be used for energy.
There are several reasons for this. Starch is held in dense granules that are not always easily accessible to digestive enzymes due to inadequate cooking or simply the physical nature of the starch structure. The resistant portion of the starch passes through the digestive system to act as soluble fiber in the colon, where it feeds healthy gut bacteria.
As a result, as described above, resistant starch contributes both directly to satiety and indirectly via a healthy microbiome (the system of gut bacteria that contribute to nutrient needs and help modulate immunity and health). Essentially, it performs like a starch when in formulation, yet in the digestive tract it behaves as a fiber.
In addition to macronutrients, certain food components increase energy expenditure without providing calories. Oolong tea is partially fermented and oxidized tea leaves, while green tea uses leaves that are neither fermented nor oxidized. Both oolong and green tea contain several polyphenolic components such as epicatechin, epicatechin gallate, epigallocatechin, epigallocatechin gallate (EGCG), and caffeine.
Thermal effects of food are often studied for their impact on metabolism. Caffeine and other alkaloid stimulants have demonstrated measurable thermogenic effects. These effects have been shown to work synergistically with tea catechins to help prevent overweight and obesity and even aid in the regulation of lipolysis and total body fat levels. (While the butter in the “butter coffee” fad diet might help contribute satiety, the caffeine in the coffee is doing the real work.
It has been shown that capsaicin, the pungent compound that fires up red hot pepper, can help lead to greater energy expenditure. It has yet to be demonstrated that the short-term increased energy cost of stimulating foods makes a significant contribution to weight management over time, however.
Mushrooms provide little energy in the way of calories, yet punch above their weight when it comes to satiation. In fact, studies on mushrooms suggest a satiating effect rivaling that of meat. A recent study published in the journal Appetite seems to confirm this.
In the study, 32 healthy participants (17 women and 15 men) consumed two servings of either mushrooms or meat for 10 days, then rated their satiety using visual analogue scales (VAS) at baseline and at regular intervals after the meal. After three hours, subjects were served lunch and allowed to eat freely. There were no differences in food consumption at the lunch.
The subjects were then given mushrooms or meat to take home for the following nine days and asked to complete diet diaries. Again, there were no significant differences in satisfaction ratings, good news for mushroom lovers. (For more on mushrooms, see “Mushrooms on Top,” July, 2018.)
Diets are inherently short-term responses to what has emerged as a long-term problem of great public health concern. Diets—especially fad diets—are no match for this global epidemic. Higher quality foods developed and provided in a sustainable and affordable manner by health-directed ingredient providers and food manufacturers is the only strategy that has a realistic hope of turning the tide.