The field of weight loss is bombarded with different diets which manipulate macronutrient composition, number of calories, timing of meals or even replacing meals and all.
Some diets work on almost the same principle (they are abolishing the old rule of ‘Fats make you fat’) but still differ. This is kind of confusing for the general populace but then again one size doesn’t fit all. (Read 5 Ways Fats Help In Weight Loss)
Each diet comes with a different science and this time we are reviewing the science behind Zone diet.
What is the theory behind Zone Diet?
The Zone Diet is devised by Dr. Barry Sears. Dr. Sears compares food to medications and suggests that the right dose should be consumed at the right time. The idea is to put your body into the ‘Zone’.
Insulin is a hormone that controls blood sugar by storing it and it is also involved in fat deposition. Glucagon also controls blood sugar but by releasing it. Eicosanoids are hormones that regulate a number of hormones and also control inflammation.
If these 3 hormones are not balanced then you are likely to gain weight and also suffer from silent inflammation.
Dr. Sears points out that your nutrition can play a key role in functioning of these hormones. This would require you to achieve a perfect balance of carbohydrate, protein and fat in every meal. The diet focuses on reducing carbohydrates and increasing protein.
Cutting down on highly sugary carbs or high glycemic index carbs can ensure proper functioning of insulin.Glycemic index is a score given to carbohydrates based on the effect they have on your blood sugar.
High glycemic index carbs are the ones that raise your blood sugar and set your hormones on a roller coaster ride, eventually making you hungry and leading to fat accumulation.
Zone diet focuses on reverse: low glycemic index carbs. The energy ratio for this diet is: 40% from carbohydrates, 30 % from protein and 30% from fat.
Zone diet is similar to most low carb, high protein diet but it allows for a larger quantity of carbohydrates then most other diets. It also concentrates on the importance of anti-inflammatory foods and omega 3 fatty acids (Read 5 Ways Omega 3 Fatty Acids Benefit In Obesity)
Dr. Sears states a number of benefits of being in the ‘Zone’:
- Quick weight loss
- Slow ageing
- Better performance
- Health maintenance
- Faster thinking
4 Benefits of Zone Diet In Weight Loss
There aren’t specific studies which test ‘Zone diet’ and its effect on body weight but a number of studies test diets similar to Zone diet. Additionally the Zone diet official website also lists scientific evidences to validate the efficacy of Zone diet.
1. Zone diet causes better weight loss than low fat diets
A study was conducted to assess the effect of reducing carbohydrates and increasing protein. The high protein group received 125g of protein. This study also reported weight loss of 7.53 kg in 10 weeks in group consuming higher amounts of protein.
Improvement in blood lipid and insulin responses was also observed. Greater satiety was reported in group consuming high protein.
Low glycemic load diet fares better than a low fat diet in terms of weight loss outcome. A study in young obese adults reported a 5.8kg decrease in weight loss in 18 months compared 1.2kg loss with low fat diet.
A diet similar to Zone diet was compared with high carb diet on obese individuals. The study lasted for 4 months. Those on diet similar to Zone diet lost 9.1% of their body weight out of which 8.7% was body fat while high carb diet led to loss of 7.3% body weight.
What does this mean?
In comparison to low fat diets which were earlier held as a total solution for weight loss, Zone diet produces better weight loss outcomes. Reducing carbohydrates and increasing protein content is the key behind this phenomenon.
You can expect to lose weight fast initially and over the weeks it could be around 1-1.5 pound each week.
2. Zone diet raises metabolism and promotes satiety
Researchers investigated the effect of high protein vs high carbohydrate diet on metabolism after a meal. Thermic effect of food is the amount of energy required to process the food.
It was observed that 2.5 hours after the meal thermogenesis rate was 2 folds higher in case of high protein compared to high carbohydrate.
One study reveals that both high protein and high carbohydrate are equally effective in reducing weight (6% loss of body weight, 9-11% loss of body fat) but satiety is higher with high protein diet.
What does this mean?
As the Zone diet favors increasing protein in place of carbohydrates, this change favors weight loss. Protein is a macronutrient that raises metabolism and promotes satiety in turn causing weight loss.
3. Zone diet improves metabolic profile
The macronutrient composition of Zone diet is beneficial for a healthy metabolic profile. The presence of low glycemic index carbs and omega 3 fatty acids along with low proportion of fats helps in improving blood lipids, blood sugar and reducing abdominal obesity.
A short term study compared the effect of low glycemic index high protein diet with AHA (American Heart Association) diet on metabolic profile. The AHA diet resulted in an increase in cholesterol: HDL cholesterol ratio which is used to assess risk of heart disease.
In contrast the low glycemic index diet resulted in 25% decrease in energy intake and did not lead to rise in cholesterol.
Researchers concluded that low glycemic index diet is favourable to treat atherogenic risk profile of abdominally obese individuals.
Researchers at UIUC found that reducing carbohydrates in diet and increasing protein helps in stabilizing blood glucose levels. 5 week treatment with Zone diet is found to have favourable impact on blood sugar level in diabetic individuals.
Austrian researchers organized a study where individuals suffering from diabetes were given a Zone like diet (protein enriched,low glycemic index load and omega 3 fatty acid supplemented diet) for 24 months.
Significant improvement in diabetes related metabolic parameter was observed. A very important outcome of this study was 4 cm decrease in waist circumference that occurred as a result of Zone diet!
What does this mean?
At times apart from weight gain, certain metabolic parameters are also affected. Zone diet effectively normalizes blood sugar control, insulin response and cholesterol. It also brings about significant reduction in abdominal obesity.
4. Zone diet may help improve exercise and athletic performance
Zone diet is said to be favourable for athletes as it results in much improved metabolic and hormonal status which supplies better oxygen to muscles and increases exercise capacity. Additionally it also improves control over blood sugar level.
However Jarvis et al report that Zone diet does not improve athletic performance. Compared to normal diet, Zone diet provided lesser calories and resulted in slight weight loss.
What does this mean?
Zone diet is recommended for improving exercise and athletic performance since it puts your body in the ‘Zone’. This produces hormones which increase oxygen supply to muscles thus increasing your stamina.
However more clinical trials are needed to prove this idea.
Zone vs. Atkins: Who wins?
The A to Z weight loss study examined the effects of popular weight loss diets (Atkins, Zone or Ornish).
Maximum weight loss was in Atkins group (8.3kg) while weight loss in Zone group was 3.7kg over a period of 1 year. Adherence was higher with Atkins compared to Zone.
Another comparative study between popular weight loss diets also reveals that weight loss is higher with Atkins diet compared to Zone diet or other diets.
However in a study comparing dietary quality of different weight loss diets, Zone diet ranked above Atkins diet.
In a 2 year long clinical trial comparing effects of popular weight loss diets on body weight and cardiac risk factors had interesting results. Average weight loss for 1 year was 2.1kg with Atkins and 3.2 kg with Zone diet, 3kg with Weight Watchers and 3.3 kg with Ornish.
Overall all the popular diet modestly reduced body weight and cardiac risk factors for a year.
The idea is not to compare only Atkins and Zone diet, most studies also give data about other diets too. But most studies reveal that Atkins fares better in terms of weight loss.
A review study assessing all such comparative studies reports that Atkins, Weight Watchers and Zone all cause similar long term weight loss but data is inconclusive to recommend only one diet.
What does this mean?
In comparison to popular weight loss diets, the data is kind of unclear. Atkins results in better weight loss outcomes acutely but on long term Zone diet is as effective as other popular diets in terms of weight loss.
How to follow the Zone Diet?
Zone diet focuses on obtaining 40% of the energy from carbohydrates, 30% from protein and 30% from fats. This is called the 40:30:30 rule. It involves consuming non starchy vegetables, little fruits, low fat protein and little fat.
To achieve the 40:30:30 ratio, Zone food blocks are developed. Each block has standardised amount of protein, fat and carbohydrate allotted to it.
Protein: 7 grams = 1 block
Carbohydrate: 9 grams = 1 block
Fat: 1.5 grams = 1 block
Depending on your body type and requirements your meal should have adequate number of blocks.
There are 1, 2, 3 and 4 block meals where 2 block meals means 2 blocks of everything (14 gram protein, 18g carbohydrates, 3g fat).
To understand this in further detail you might want to invest in a Zone diet book. Apart from this the Zone lab also provides omega 3 fatty acids and other dietary supplements, which if taken with Zone diet enhance its anti-inflammatory effect.
What is the easiest way to follow Zone diet?
Dr. Sears mentions an easy way of following the Zone diet without the extensive calculation. He says at each meal, one should divide their plate into 3 sections.
One section should be filled with low fat protein about the size of your palm (which would be around 3 ounces for women and 4 for men).
Then 2/3 of the plate should be filled with colourful carbohydrates which is non starchy vegetables and fruits. Finally add a dash of fat that is low in saturated fats and omega 6 fatty acids. That would be olive oil or some nuts.
Here is what you can eat on Zone diet:
- Carbohydrates: Mainly low glycemic index carbohydrates like beans, cabbage, broccoli, artichoke, berries, apples, grapefruit etc. Other carbs like bread, sugar, pasta, rice, carrots, bananas are discouraged but can be consumed if they fit the block pattern.
- Protein: Low fat protein like fish, chicken, turkey, soy products and lean cuts of meat
- Fats: Olive oil, Canola oil, Sesame oil, nuts, almond and peanut butter
Advantages & Drawbacks of Zone diet
If you were to have a look at the pro and cons of Zone diet, then here is how it goes:
- Cuts down on sugary and high glycemic index carbs
- Includes good carbs like vegetables and fruits
- Allows for more protein
- Emphasizes on the value of omega 3 fatty acids
- Takes into account the role of hormones and weight gain
- Very structured pattern
- Involves a lot of measuring and calculation
- Cuts down on fats to a great extent
- Cuts down on nutritious foods like grains which can be eaten in moderation
Just like most popular diets, Zone diet recommends eating healthy food by varying macronutrient composition. It suggests raising protein quantity in the diet and eating carbohydrates but mostly low glycemic index ones.
This is fairly a good idea especially for those who don’t want to abandon carbs totally or for those who suffer from metabolic issues and also for those who are not comfortable with severe restriction of any particular food type.
However, the diet requires too much of effort to follow in terms of measurement and calculation. This would cause loss of interest in the diet. If you tried Zone diet it would be great if you could share your experience with us.