#1. Prepackaged Meal Plans
Like many meal-selling diets they sell the consumer / dieter prepackaged meals typically composed of lean protein, lots of vegetables and full grains.
In theory, the diets do work on the principle that the person only consumes the prepackaged food that is sold to them from the company - and cuts the total number of calories a person is eating while still providing all the nutrition an individual needs.
And the food is shipped to you via FedEx - at which point you have to ask, how good is the food if it is sent via a courier and not stored in a freezer en route???
$460 + shipping for four weeks of food - when people could just go buy healthy food at the grocery store for less and take cooking classes on how to make healthy food.
Price Comparisons
Jenny Craig - $15 Monthly fee + $25 Enrollment fee + the cost of food. Cost of food is $420 to $644 for 4 weeks. So it can be slightly less or possibly more than the South Beach Diet.
Nutrisystem - $275 to $577 for 4 weeks, depending upon promo deals and the menu chosen.
Conclusion - All these companies really want to do is sell you food for an outrageous price. What they really should all be doing is selling their food in grocery stores like other food manufacturers, but at a more reasonable price. That way everyone has the option to buy their food items, and at a reasonable price.
#2. Calorie Watching Point System
Weight Watchers has a number of similarities to Jenny Craig, but they don't actually sell you food. Instead they rely on meetings and hanging out with other people who are also going through the Weight Watchers program, and it involves a Point System for how much food you are allowed to eat.
Each day a dieter gets X number of points and they spend those points eating whatever they want, but they only have so many points to spend. Unhealthy foods cost more points. Healthier foods cost less points. Sounds easy, right?
Weight Watchers - $35 Signup fee + weekly fees of $3.45 to $8.67 per week, depending on whether you do online or in-person meetings.
So the meetings work a bit like Alcoholics Anonymous, except it is focused on people who have problems controlling their eating habits. Using the Point System, participants limit their daily intake of calories and use the online support system / meetings to gain positive reinforcement so that gain the mental courage and determination to stick with the diet.
Conclusion - The support system is really what the person is paying for. In theory people could get a lot of the same support from Weight Loss Facebook groups, Meetup Groups for people into dieting/exercising, and similar websites / organizations that operate for free and non-profit.
#3. The Glycemic Index Diet
In the G.I. Diet foods are assigned numbers according to their glycemic index (GI). The higher the GI number, the greater the blood-sugar response. Promoters of the diet claim that low GI foods, such as lentils, can help control your appetite because they're digested and absorbed more slowly - however there is a lack of research on this topic and no real proof that their a connection between lower glycemic levels in food and appetite suppression.
Part of the theory behind this diet is that some low GI foods are nutrient rich, high in fibre and contain unrefined sugars - however that isn't true for all foods. Some low GI foods are still really unhealthy for you. For example French Fries has a lower GI than a baked potato, but that doesn't mean they are good for you.
Conclusion - In theory this diet works some of the time, but it needs to be taken with a mental grain of salt and the wisdom to say no to foods a person knows to be unhealthy, which means it really comes down to moderation and willpower to make this diet successful.
#4. The Zero Carbs or Low Carbs Diet
Various low carb and zero carb diets include notables likes The Atkins Diet, however they all follow the same principle of pointing the blame at carbohydrates - which are frankly in almost everything. If it has carbon and water in the food, then it contains carbs.
It is basically just another way of steering people away from calories, as foods that contain lots of carbs tend to be high in calories - such as bread, pasta and rice.
Similar diets like the Paleo Diet (aka, the Caveman Diet) follows the principle of only eating foods that a caveman would eat, such as vegetables, berries, fruits and meat. Nothing processed and nothing baked (so no bread).
And then there is the Raw Food Diet - which takes the Paleo Diet one step further, but also cuts only a lot of meat that would normally be cooked. So instead a person is reduced to only eating any fruit or vegetable (and possibly raw sushi) that is uncooked and heated no more than 48 degrees Celsius.
However all three of these diets say it is okay to eat avocados - a very fatty fruit - and various other foods that are not healthy either.
The principle of all three diets, Atkins, Paleo and Raw Food is to steer people away from high carb foods like bread, pasta, rice, etc. However the body still needs carbs for energy. You cannot get rid of them completely, plus carbs expand in your belly and make a person "feel full", which in turn reduces a person's appetite.
Conclusion - So eating carbs is technically okay, but it comes back to the moderation and willpower issue again. People can potentially get weight loss success with these diets, but they have to do it smart and the question then becomes, what now after they lose the weight?
#5. Reverse Dieting
Okay, so technically this is not a Fad Diet. I snuck this one in year because almost no one ever does this. Reverse Dieting is what you SHOULD be doing after you successfully lose weight.
You have lost the weight already, but how do you keep it off instead of yo-yo-ing back to your previous weight?
That is where Reverse Dieting comes in, and sadly almost nobody does this - which is why many people end up regaining weight and seeing weight fluctuations over the course of years.
Your goal during Reverse Dieting is to stabilize your eating habits and your weight so that they become a constant. This process takes months to achieve.
After completing a diet a person typically returns to older eating habits, but their stomach is still roughly the same size as it used to be. Unless they somehow lost weight slowly and gradually, their stomach is probably still the same size. They need to continue eating lesser amounts of food until their stomach shrinks down to a size that matches their new body.
One way to do this is to count calories and incrementally increase the amount of food a person eats only their body-weight stabilizes.
Example
If a person was eating 1400 calories per day and losing 1 lb of fat per week and then they reach their desired weight. Their old diet was 2500 to 2800 calories per day, which was clearly way too much. If they just went back to their old diet, they would end up regaining the weight in a hurry.
Instead, knowing how much they were consuming during the diet they should now incrementally increase their diet until their weight stabilizes, such as increases it to 1500 calories per day for 1 month and keeping a record of their weight fluctuations during that month.
At the end of the month they see that they have still lost a few pounds of fat, which means they need to incrementally increase their diet again, this time to 1600 calories per day.
The goal then is to keep doing this each month until their weight stops fluctuating and remains a constant.
Once the constant has been reached a person should keep track of their calories for 6 months or more so that their stomach and eating habits permanently adjust to their new diet. Thus their diet becomes complete.
Conclusion - A key component of Reverse Dieting is maintenance and vigilance. All other diets are basically useless unless a person also learns how to keep the weight off and maintain their ideal weight.
