Let’s go have a burger, but make the bun whole grain please! Ok, so fat is now in and carbs are out. It seems like there’s research to support any diet you choose to follow. Are we getting smarter or just making things so confusing people just throw their arms up in the air, say “screw that” and just eat whatever their heart desires.
But, if you desire your heart, you might want to read this to get some clarity on the controversy.
The Prospective Urban Rural Epidemiology (PURE) study, reported in ScienceDaily.com, asked dietary questions to over 135,000 low, middle and high income people over a 10-year period from Africa, North America, South America, Asia and Europe.
There were three parts to the PURE study. One looked at the impact of dietary fats on clinical outcomes while another focused on the consumption of fruits, vegetables and legumes in relation to death, heart disease and strokes. The third component, reported in The Lancet Diabetes and Endocrinology, looked at the impact of dietary fats and carbohydrates on blood lipids and blood pressure.
A summary of the data released in August, revealed that a diet consisting of a moderate amount of fat, fruits, vegetables and legumes and avoidance of a high proportion of carbohydrate was associated with a lower risk of death.
The results were surprising and not in accordance with the current dietary guidelines of dietary fats making up 30% or less of total calories, carbohydrates making up 50% and fats making up the rest while keeping saturated fats to less than 10% of daily calories.
Making sense of the PURE data
Actually, the results do make sense. The lead researcher, Mahshid Dehghan, in an interview with Science Daily said:
“A decrease in fat intake automatically led to an increase in carbohydrate consumption and our findings may explain why certain populations such as South Asians, who do not consume much fat but consume a lot of carbohydrates, have higher mortality rates.”
Many of the participants were low income and ate a diet consisting heavily of white rice and lower on animal products and produce. White rice is a high glycemic food – making blood sugars skyrocket with each additional serving. Animal products are high in protein and produce is high in fiber which slows down digestion and the rise in blood sugar.
If you look at the graph of macronutrients below, you’ll notice that carbohydrates make the blood sugar spike with a steeper parabola than protein and fat. The larger the portion of a simple carbohydrate like white rice, and not combined with much protein or fat, the quicker and larger the blood sugar rise which puts stress on the pancreas to make more insulin to take care of the extra glucose in the blood stream. Eventually, this leads to damage of the arteries and an impaired pancreas, and an earlier death.
Blood sugar and lipid connection
When you eat a lot of processed, white carbs – like white pasta, rice, bread, and crackers – your body quickly digests them and converts them to glucose. Your body can use some of this glucose for fuel, but any extra gets stored in the form of triglycerides.
Findings from the third study also found that a high carbohydrate diet, particularly one with refined grains, was associated with a lower good cholesterol – HDL – which is heart-protective.
A low HDL and high triglycerides are two of the five components of metabolic syndrome – one more of the 5 components and you’ve got heart disease and diabetes in your future.
Glycemic Index and your blood sugar
There are “good” and “bad” carbs. Well, maybe there are some “bad” or unhealthy carbs that really taste good, darn it. I love you Holy Donut. But there are also some “good” carbs that also taste good.
Carbs that are lower in glycemic index are much healthier for you as explained below. Low glycemic foods include legumes like lentils, steel-cut oats, whole grain pasta, fruits and non-starchy veggies. Do you think donuts could taste as good if they were made with whole oat flour and baked instead of fried?
High glycemic foods are all your “white” foods including russet potatoes, pretzels, popcorn, rice cakes and melons and pineapple.
So, a plate of white pasta, which can be as much as four times the recommended serving, with tomato sauce (and most have added sugars), will shoot your blood sugar way up. A large bowl of Rice Chex with milk will do the same thing. Both meals are high in low glycemic carbohydrates and low in protein, fiber and fat.
The rise in blood sugar will cause your body to release extra insulin that will cause your blood sugar to plummet, as you can tell by the graph on the right. In fact, your blood sugar can drop down lower than normal, triggering an adaptive response by your body to get your blood sugar back up to normal. This adaptive response releases epinephrine leading to shakiness, irritability and even a headache. So, you go from food coma to nervous Nellie – that’s an emotional roller-coaster I wouldn’t want to be on.
What you can do
The findings from the PURE study are logical. The important message here is to:
- Pay attention to portion sizes of your carbohydrates – use the food label to become aware of a serving size.
- Make at least half of your carbs low-glycemic, moving away from the “whites”.
- Include a source of protein – low-fat Greek yogurt, low-fat cheese, poultry, fish or lean meat with your meals and snacks.