Back to the Basics: Hormone Control With Protein Every fitness professional you talk to seems to have a different idea on what the best method to shed bodyfat is. Some tote two cardio sessions a day, other proclaim cardio is not necessary and it’s all about the diet. Still others turn to a combination of both high intensity interval training cardio with a well planned out diet. Truth be told, all of these methods do work to some degree but some may be more advantageous than others.
One increasingly popular method is a high protein-high saturated fat diet at the expense of energy providing carbohydrates. Now I know many of you are cringing right now at the thought of feasting on chicken breasts and canned tuna for the next few weeks of your life but hold on a second, this theory may offer some promise.
In a study done by Manny Noakes et al. (2006), three groups of subjects were assigned to three different diets for a period of time to compare how macronutrient composition affects both body fat loss as well as cardiovascular risk. It has been speculated that obesity, often caused by diets high in refined carbohydrates, is the precursor to cardiovascular risk. Therefore one would think a low carbohydrate diet would be the answer but many feel high protein diets are too high in saturated fat and are dangerous as well. So what is the answer?
This study attempted to clear up some of the confusion. The three different diets were all isocaloric, meaning each group of subjects took in the same amount of calories therefore any changes demonstrated were strictly attributable to various macronutrient manipulation. All subjects also displayed at least one symptom marker for cardiovascular disease risk. They maintained this diet for a period of 12 weeks, 8 of those weeks being an intensive restricted period with a 30% caloric deficit (took in 30% less calories than what they needed to maintain their current weight) and 4 more weeks at a maintenance level. The groups were divided up into VLF (very low fat: 70% carbohydrate, 10% fat (3% saturated) and 20% protein), HUF (high unsaturated fat: 50,30 (6), and 20, respectively), and VLCARB (4, 61 (20), and 35).
Each diet consisted of the following:
|Cheese, full fat||70||High fiber Cereal||40||High fiber cereal||32|
|Milk, full fat||125||Bread, Wholegrain||105||Bread, wholegrain||70|
|Lean meat, Chicken||350||Low fat biscuits||60||Milk, skim||300|
|Eggs||2||Milk, skim||250||Cheese, full fat||20 g/2 week|
|Very low carb vegetables||2 cups||Cheese, low fat||20||Yogurt, skim||200 grams X 3/week|
|Almonds||50||Rice or pasta, dry||50||Pasta and rice, dry||100 grams X 4/week|
|Butter||20||Fresh fruit||300||Nuts, mixed||20|
|Dried fruit||50||Salad vegetables||100|
|Lean meat, chicken||100||Fresh fruit||300|
|Salad vegetables||100||Pulses, cooked||100|
|Low carbohydrate vegetables||2 cups||Lean meat, chicken||150|
|Tuna||50 grams X 2/week|
|Low carb vegetables||1.5 cups|
|Potato||1 X 3/week|
|Unsaturated oil or margarine||25|
Throughout the diet, a variety of blood tests were performed to determine effects taking place. Samples were taken at the beginning, after 4 weeks, after 8 weeks and after it was over, at 12 weeks. Venous blood samples were collected in the morning after fasting during the night to establish glucose, ketone, insulin and lipid concentrations in the plasma. Fasted lipid measurements were taken for two days in a row, averaged and then reported for each specified reading. Another venous blood sample was taken at week 0 and 12 to determine homocysteine, folate, and B12.
Urine tests were also completed daily for the assessment of urea/creatinine ratio, calcium and sodium and potassium excretion. Deoxy-pyridinonine/creatinine and pyridinonine/creatinine ratios were collected, which are biomarkers of bone turnover rate (Manny Noakes et al, 2006).
At the beginning and end of the study, body composition was done using DEXA readings, along with an oral glucose tolerance test and the next day, a 3 hour meal tolerance test (with meals that were representative of the diets the subjects were placed on). During this meal tolerance test, readings for venous blood levels of glucose, insulin, and free fatty acid concentrations were taken 30, 60, 120 and 180 minutes after the meal.
After analysis of the samples taken, very interesting results were seen. Plasma ketones changed between diets, with the VLCARB diet producing the highest levels of ketones compared with the HUF and VLF diets. All three groups lost an average of 8 pounds of net weight during the 8 weeks on the restricted diet and then maintained this loss for the 4 weeks following in the maintenance stage. What is interesting to note however is that there was a significant difference in lean tissue weight loss between the VLCARB diet and then HUF and VLF diets, the former maintaining more muscle tissue. DEXA did not find there to be any significant difference in where the subjects lost their body mass from though.
With regards to cardiovascular disease markers, the biggest observation was the effect the diets had on LDL-C and HDL-C with a net increase on the VLCARB diet but a net decrease on the other two diets. The effects of diet on ApoB concentrations was not altered. Triglyceride levels were also affected by the different diets, with VLCARB decreasing them the most, followed by HUF and then VLF.
Plasma folate readings were unchanged by any of the diets and plasma homocysteine increased by 6.6% on the VLCARB diet, decreased by 6.8% on the VLF diet and remained unchanged on the HUF diet (Manny Noakes et al., 2006).
Fasting glucose decreased by 2% with weight loss regardless of which diet the subjects followed while fasting insulin levels were greatly affected with a 33% decrease with VLCARB, 19% decrease with HUF, and 15% increase on VLF diets. Weight loss increased glucose tolerance in both the HUF and VLF diets but remained unchanged in the VLCARB diet, however during the fasting meal test, insulin response was markedly lower following the VLCARB diet in comparison to the other two.
Calcium excretion increased on both the VLCARB diet (25%) and decreased on the other two diets (12-16%), sodium remained stable, and postassium excretion only increased on the VLF diet.
So What Does This Mean?
How does one go about interpreting these results now and how can you apply them to your training. Well first off, it appears as though there may be a metabolic advantage to consuming a very low carbohydrate diet as there was a greater proportion of fat loss and lean muscle retention than with either a very low fat or high unsaturated fat diet. The proposed reasoning behind this, is when on a very low carb diet, you are reducing your plasma insulin levels and sparing body protein by minimizing the need for gluconeogenesis.
The next finding of this study that may be of particular importance to some of you out there is the benefits it can have on people with diabetes or people who are trying to control their insulin levels. Insulin levels were remarkable stable on the VLCARB diet, meaning that you did not see barely any swing in blood sugar levels after eating, something that is critical for managing diabetes. Also, interestingly enough, after consuming a LCARB diet for a period of time, glucose tolerance goes up considerably, meaning if you were to consume a load of glucose, your body would be better equipped with handling it than if you had been eating a low fat, higher carb or high fat, moderate carb diet.
One fact that was observed in this study is that LCARB diets tend to increase calcium excretion. Some people may get concerned over this thinking that it will mean you set yourself up for osteoporosis, however, the fact remains that low carb dieters also typically take in more dairy products, thus get more calcium overall and also have an
easier time increasing muscle mass which helps to offset osteoporosis.
Another thing that may worry some people is that high protein diets are associated with heart disease and kidney failure. Manninen (2004) stated however that there is no scientific evidence to prove this thus far, even when protein intakes are 2-3 times higher than the Recommended Daily Allowance. Even diabetics should not worry about limiting their protein intakes to less than 20% according to Manninen. During a high protein diet test with diabetics, their glycated hemoglobin was found to decrease 0.5% from those who were on a low protein diet (15% compared with 30%).
So to sum things up, if you are looking to lose bodyfat and retain as much muscle as possible, or are diabetic or suffer from symptoms of hypoglycemia, low carb diets might work for you. Not everyone will respond the same way to a diet, however research points that this one improves insulin and glucose regulation and can improve symptom markers for cardiovascular risk.
1. Manny Noakes, et al. (2006). Comparison of Isocaloric very low carbohydrate/high saturated fat and high carbohydrate/low saturated fat diets on body composition and cardiovascular risk. Nutrition and Metabolism, 3:7.
2. Manninen, Anssi. (2004) High Protein Weight Loss Diets and Reported Adverse Effects: Where Is The Evidence? Sports Nutrition Review Journal 1(1):45-51.