When it comes to losing weight, there are nearly as many weight loss programs as there are people trying to lose weight! Some tout eating particular foods, while others advocate avoiding specific or even categories of foods.
One popular idea is the high-protein diet, which was strongly advocated by Dr. Atkins several decades ago. While the Atkins plan pushed more for no to little carbs than high protein, it was the excess protein that had some people concerned.
How much is too much is and is there such a thing as too little, especially when it comes to weight loss?
Finding the Right Ratio
Two Canadian researchers questioned this very thing. They wondered which of three diets would be most effective in terms of weight loss and biomarkers of metabolic syndrome in overweight women.
They divided 54 overweight or obese women into one of three groups:
- Low protein (1 gram of protein for every 4 grams of carbohydrates)
- Normal protein (1 gram of protein for every 2 grams of carbohydrates)
- High protein (1 gram of protein for every 1 gram of carbohydrates)
Additionally, all three groups cut nearly 30 percent of their calories, and no more than 30 percent of those calories were to come from fat. They were also encouraged to focus their meals on fresh, whole foods as opposed to pre-packaged, processed foods, junk food, fried food, sugary products, or high-fat red meat. To keep track of this, all participants were asked to complete daily food journals, documenting the amount of protein and carbs they consumed each day.
Participants did a one-hour fitness program three days a week. The fitness program consisted of the following:
- A nine-minute warm-up
- Thirty minutes of circuit training, alternating between resistance training and aerobic exercise
- Twenty-one minutes of abdominal exercises and flexibility stretches
They began the exercise program at 65 percent of their maximum heart rate for the first three weeks and worked their way up by 5 percent every three weeks until they reached 80 percent by the end of the study.
Finally, researchers tested several biomarkers of obesity and metabolic syndrome, including:
- Height and weight
- Waist and hip circumference
- Blood pressure
- Heart rate
- Body composition
- Glucose levels
- Cholesterol levels
- Nitrogen balance
Does Protein Matter?
At the end of the 12 weeks, researchers found that all participants lost a significant amount of weight, with the normal protein group losing a bit more than the low-protein and high-protein groups. Similarly, all groups reduced their BMI and enjoyed significant decreases in body fat. However, those in the normal protein group lost more total body fat as a percentage of total weight than the women in the low- and high-protein groups.
When it came to waist circumference, those women in the normal protein group lost 11.6 centimeters, as compared to just 7.9 in the low-protein group and 8.6 in the high-protein group. For hip circumference, the normal protein group lost 8.8 centimeters, with just 7.4 lost in the low-protein group. The high-protein group fared a bit better with 8.4 centimeters lost.
On the blood pressure front, those in the high-protein group saw a significant reduction in systolic blood pressure (10.6 mmHg), as compared to the low-protein group (8.7 mmHg) and the normal protein group (8.1 mmHg). Numbers were closer when it came to diastolic blood pressure, with decreases measuring in at 5.4 mmHg, 5.7 mmHg, and 5 mmHg for the low-, normal, and high-protein groups, respectively.
Resting heart rate decreased across all groups, with the normal protein group seeing the largest reduction at 13 beats per minute (bpm). The low group had a mere 5.6 bpm reduction and the high group enjoyed an 8.8 bpm decrease.
While there were no significant differences in fasting glucose levels, insulin levels decreased significantly in the high-protein (71 pmol/l) and normal protein groups (66 pmol/l). The low-protein group had a modest 43 pmol/l reduction in insulin levels.
All groups saw reductions in triglycerides, total cholesterol, and LDL cholesterol levels, though the differences between groups were not significant. Similarly, HDL cholesterol levels increased in all groups, but with no significant differences among the three diet plans.
Finally, there were comparable increases in creatinine levels (indicator of kidney function) across the groups. But when it came to nitrogen balance (another indicator of kidney function), the low-protein group had the greatest reduction with 4.0. The normal group had less than half that reduction at 1.74, while the high-protein group had a miniscule 0.34 decrease.
Based on these results, researchers concluded, “There were no significant differences between the diets, in the weight loss achieved. Thus, the present trial supports the idea that total energy intake, rather than the macronutrient composition, is the most important determinant of weight loss.”
Protein Actually DOES Matter
While the numbers of the various biomarkers denote overall losses across the three diets, there were a few areas where the normal protein diet seemed to stand out, namely:
- Total body fat
- Waist and hip circumference
- Resting heart rates
However, the one area that really made the normal protein diet shine was compliance. Those women asked to eat a 1:2 ratio of protein to carbohydrates found it much easier to stick with the diet than those women eating the 1:1 or 1:4 ratios. And sticking to a diet, ultimately, is the key to successful weight loss.
Therefore, if you are looking for a weight loss program that not only works but is realistic, then take a note from this study. First, reduce your current calorie load by 30 percent. Next, make sure that less than 30 percent of your overall caloric intake comes from fat. And, finally, aim for one gram of protein for every two grams of carbohydrates.
 Campbell, DD and Meckling, KA. Effect of the protein:carbohydrate ratio in hypoenergetic diets on metabolic syndrome risk factors in exercising overweight and obese women. Br J Nutr. 2012 Jan 16:1-14. [Epub ahead of print.]