Reducing the amount of carbs you eat is one of the best ways to lose weight.
It tends to reduce your appetite and cause “automatic” weight loss, without the need to count calories.
This means you can eat until fullness, feel satisfied and still lose weight.

The dietary guidelines recommend that carbs provide 45 to 65 percent of your daily calorie intake.
So if you eat a 2000-calorie diet, you should aim for about 225 to 325 grams of carbs per day.
But if you need to lose weight, you will get much faster results eating around 50 to 150 grams of carbs.
In fact, a popular alternative called the low-carb diet has been shown to be much more effective for weight loss than the high-carb diet that has been recommended for the past few decades.
This diet restricts your intake of carbohydrates like sugars and starches (breads, pasta, etc.) and replaces them with protein, fat and healthy vegetables.
Studies show that low-carb diets reduce your appetite and make you eat fewer calories and lose weight pretty much effortlessly, as long as you manage to keep the carbs down (1).
In studies where low-carb and low-fat diets are compared, the researchers need to actively restrict calories in the low-fat groups to make the results comparable, but the low-carb groups still usually win (2, 3).
Low-carb diets also have benefits that go way beyond just weight loss. They lower blood sugar, blood pressure and triglycerides. They raise HDL (the good) and improve the pattern of LDL (the bad) cholesterol (4, 5).
Low-carb diets cause more weight loss and improve health more than the calorie restricted, low-fat diet still recommended by many people. This is pretty much a scientific fact at this point (6, 7, 8).
SUMMARY:There are many studies showing that low-carb diets are more effective and healthier than the low-fat diet that is still recommended by many people.

How to Figure Out Your Need For Carbohydrates

There is no clear definition of exactly what constitutes a "low carb diet" and what is "low" for one person may not be "low" for the next.
An individual's optimal carb intake depends on age, gender, body composition, activity levels, personal preference, food culture and current metabolic health.
People who are physically active and have more muscle mass can tolerate a lot more carbs than people who are sedentary. This particularly applies to those who do a lot of high intensity exercise like lifting weights or sprinting.
Metabolic health is also a very important factor. When people get the metabolic syndrome, become obese or get type II diabetes, the rules change.
People who fall into this category can't tolerate the same amount of carbs as those who are healthy.
SUMMARY:The optimal carb intake varies between individuals, depending on activity levels, current metabolic health and many other factors.

Decide Your Daily Carb Intake

If you simply remove the unhealthiest carb sources from your diet, refined wheat and added sugars, then you'll be well on your way to improved health.
However, to enjoy the full metabolic benefits of low-carbohydrate diets, you also need to restrict other carb sources.
Even though there is no scientific paper that explains exactly how to match carbohydrate intake to individual needs, I have personally found these guidelines to be very effective.

100-150 Grams per Day

This is more of a "moderate" carbohydrate intake. It is very appropriate for people who are lean, active and are simply trying to stay healthy and maintain their weight.
It is very possible to lose weight at this (and any) carb intake, but it may require you to count calories and/or control portions.
Carbs you can eat:
  • All the vegetables you can imagine.
  • Several pieces of fruit per day.
  • Moderate amounts of healthy starches like potatoes, sweet potatoes and healthier grains like rice and oats.

50-100 Grams per Day

This range is great if you want to lose weight effortlessly while allowing for a bit of carbs in the diet. It is also a great range to maintain your weight if you are sensitive to carbs.
Carbs you can eat:
  • Plenty of vegetables.
  • 2-3 pieces of fruit per day.
  • Minimal amounts of starchy carbohydrates.

20-50 Grams per Day

This is where the metabolic benefits really start to kick in. This is the perfect range for people who need to lose weight fast, or are metabolically deranged and have obesity or diabetes.
When eating less than 50 grams per day, your body will get into ketosis, supplying energy for the brain via so-called ketone bodies. This is likely to kill your appetite and cause you to lose weight automatically.
Carbs you can eat:
  • Plenty of low-carb vegetables.
  • Some berries, maybe with whipped cream (yum).
  • Trace carbs from other foods like avocados, nuts and seeds.
Be aware that a low-carb diet is NOT no-carb. There is room for plenty of low-carb vegetables (full list here). Personally I had never eaten as many veggies as when I first started on a low-carb diet.

Important to Experiment

We are all unique and what works for one person may not for the next. It is important to do some self-experimentation and figure out what works for you.
If you have a medical condition, then make sure to talk to your doctor before making any changes, because this diet can drastically reduce your need for medication!
SUMMARY:For people who are physically active or want to maintain their weight, a range of 100-150 grams of carbs per day may be optimal. For people who have metabolic problems and need to lose weight quickly, going under 50 grams per day is a good idea.

A low-carb diet isn't just about weight loss, it is also supposed to improve your health.
For this reason, it should be based on real, unprocessed foods and healthy carb sources.
So-called "low carb junk foods" are a bad choice.
If you want to improve your health, then choose unprocessed foods: meats, fish, eggs, vegetables, nuts, avocados, healthy fats and full-fat dairy products.
Choose carbohydrate sources that include fiber. If you prefer a "moderate" carb intake then try to choose unrefined starch sources like potatoes, sweet potatoes, oats and brown rice.
Added sugar and refined wheat are always bad options and should be limited or avoided.
For more details on specific foods to eat, check out this list of low carb foods and this detailed low-carb meal plan and sample menu.
SUMMARY:It is very important to choose healthy, fiber-rich carb sources. There is room for plenty of vegetables, even at the lowest level of carb intake.
Low-carb diets greatly reduce your blood levels of insulin, a hormone that brings the glucose (from carbs) into cells.
One of the functions of insulin is to store fat. Many experts believe that the reason low-carb diets work so well, is that they reduce your levels of this hormone.
Another thing that insulin does is to tell the kidneys to store sodium. This is the reason high-carb diets can cause excess water retention.
When you cut carbs, you reduce insulin and your kidneys start shedding excess water (9, 10).
It is common for people to lose a lot of water weight in the first few days on a low-carb diet, up to 5-10 pounds.
Weight loss will slow down after the first week, but this time the fat will be coming from your fat stores.
One study compared low-carb and low-fat diets and used DEXA scanners (very accurate) to measure body composition. The low-carb dieters lost significant amounts of body fat and gained muscle at the same time (11).
Studies also show that low-carb diets are particularly effective at reducing the fat in your abdominal cavity (belly fat), which is the most dangerous fat of all and strongly associated with many diseases (12).
If you're new to low-carb eating, you will probably need to go through an adaptation phase where your body is getting used to burning fat instead of carbs.
This is called the "low-carb flu" and is usually over within a few days. After this initial phase is over, many people report having more energy than before, with no "afternoon dips" in energy that are common on high-carb diets.
SUMMARY:It is common to feel suboptimal in the first few days of lowering your carb intake. However, most people feel excellent after this initial adaptation phase.
If you want to try this out, then I recommend that you try tracking your food intake for a few days to get a "feel" for the amount of carbs you are eating.
My favorite app for this is called Cron-O-Meter. It's free and easy to use.
Because fiber grams don't really count as carbohydrates, you can exclude the fiber grams from the total number. Instead, count net carbs (net carbs = total carbs - fiber).
However, one of the great benefits of low-carb diets is that they're ridiculously simple. You don't need to track anything if you don't want to.
Just eat some protein, healthy fats and veggies at every meal. Throw in some nuts, seeds, avocados and full-fat dairy products for good measure. Choose unprocessed foods. It doesn't get much simpler than that!