Research Review: 2 years of low-carb – what happens? |

2 years ago, I declared that, after 26 years of being a gimpy vegetarian, I was going to go low-carb. I lost some weight initially, but after a few months, it came back, plus another 15 lbs. I gave up on low-carb, and got back on the gimpy vegetarian diet.

For the past two years, I have been trying to lose weight and keep it off, without low-carb dieting. It has been difficult to say the least, and I have lost a lot of weight (and gained a lot of it back again). I have spent a lot of time researching the low-carb diet, and reading online literature from various sites and publications. I am going to update this review over the next few weeks, and give my opinion on the long-term effects of a low-carb diet on a bodybuilder.

In Western society, lipophobia – the fear of fat – prevails.

How else do you explain your colleague cheerfully consuming a fatless neon pink cotton candy and swallowing it with Coke while exclaiming: Don’t you know that avocados are very rich in fat….. If you eat a salad with chicken, spinach and avocado with a dressing of olive oil.

Well, I’ll try the avocado.

I’m not a fan of bacon and salami with two pieces of bacon, but I do prefer good sources of fat like avocados, nuts, coconuts, olives and oily fish like salmon.

I thought we were done with the nonsense about avoiding fat, but lately I feel like I’m surrounded by anti-fat advocates. Let’s look at the evidence.

Low-carbohydrate diet What do we know so far?

A few years ago, an article was published that compared five different studies to determine what we really know about low-fat and low-carb diets (1).

Most studies on low-fat diets allowed up to 30% of daily calories to be from fat, and one study involved a very low-fat diet (<10% of daily calories from fat). In the low-carb diet studies, carbohydrates were limited to 20 grams per day.

After comparing and summarizing five studies with 447 dieters, it was concluded that low-carbohydrate, energy-restricted diets were at least as effective as low-fat, energy-restricted diets after one year.

Translation: If you eat a lot less carbs, you won’t have to watch the total number of calories as much to lose weight as if you counted calories and fat. But you can’t eat pounds of butter and expect to get slim.

Well, that’s a good start. But what about the long-term results? I’m glad you asked!

Research question

This week I’m looking at a brand new study that compared low-carb and low-fat diets for two years.

Foster, GD, et al. Weight and metabolic parameters after 2 years of following a low-carbohydrate diet versus a low-fat diet: a randomized study. Ann Intern Med. 2010 Aug 3;153(3):147-57.


The researchers wanted to know which diet – low-fat or low-carb – was better for long-term weight loss and overall heart health.

They first found 307 volunteers in their 40s who were obese (BMI>30 kg/m2). People with type 2 diabetes and/or high blood pressure or who used medication against obesity or cholesterol did not participate in the study. In fact, the study looked at people who were as healthy as they could be, but were obese.

Half of the participants were put on a low-fat diet (154 participants) and the other half on a low-carbohydrate diet (153 participants).

Low-carb diet

The low-carb group had to consume 20 grams of carbohydrates per day (80 calories), all from low-glycemic vegetables. Asparagus, broccoli, Brussels sprouts, spinach and celery are among the vegetables with a low glycemic index (less than 20).

Fruits, breads, pasta and vegetables with a high glycemic index (carrots, corn, potatoes, pumpkin, sweet potatoes) were banned, but the emphasis was not on calorie restriction. The subjects were asked to eat high-protein and high-fat foods until they were full. These recommendations are based on phase 1 of Dr. Atkins’ New Revolution diet, which limits carbs to 20 grams.

After 12 weeks, carbohydrates were reintroduced at a rate of 5 grams per day per week. Week 13 allows 25 grams of carbs per day, week 14 30, and so on, adding more vegetables, fruits, and grains. The same recommendations were part of the guidelines of the Atkins diet.

Low-calorie diet

While a low-carb diet focuses on carbohydrates, a low-fat diet focuses on calories. Since fat has the most calories per gram (9 calories per gram), you can reduce calories by limiting fat to protein and carbohydrates (4 calories per gram).

The women were told to eat 1200-1500 calories a day and the men 1500-1800 calories a day.

The distribution of calories was as follows:

  • 55% of calories come from carbohydrates
  • 30% of calories come from fat
  • 15% of calories come from protein

There was an exercise… like.

Most diet studies do not involve exercise, so people end up losing 10 pounds (about 5 kg) in a year.

In this study, subjects participated in physical activity from week 4, at a rate of 4 sessions per week. The workout consisted mainly of 20-minute running drills. By week 19, everyone was doing up to 4 50-minute sessions per week (3 hours 20 minutes total, still less than the 5 hours per week JB recommends).

Keep everyone informed

Two years is a long time to learn.

Follow-up examinations were conducted at 3 months, 6 months, one year and two years after the start of the diet to check body composition (percentage of body fat), blood tests, blood pressure and total weight.

Because the study was so long, they had to keep track of all the subjects somehow, so the researchers put all the subjects into one group:

  • every week for the first 20 weeks, then
  • every two weeks for the next 20 weeks, and then…
  • every two months until the end of the study.

During these meetings, the group discusses behavioral therapies such as self-control, what to do when you collapse, and how to deal with temptations.


Body weight

In the first three months, the low-carb group lost an average of just under 10 kg (9.49 kg, 20.9 lbs). The low-fat group also did well, but lost less weight – they lost 8.37 kg (18.5 lbs).

From the age of 6 months, there was no real difference in weight loss between the two diets. Both groups regained weight gradually and both groups lost a total of 7 kg after 2 years. It’s not really a story of successful weight loss.

Figure 1 – Weight loss over 2 years in people following a low-carbohydrate and low-fat diet.

Both groups lost body fat and lean mass in the same proportion. Yes, just over 2 kg of the 7 kg weight loss is fat free mass.

Cardiovascular risk factors

During the first six months, those who followed the low-carb diet had a lower risk of cardiovascular disease as triglyceride and LDL levels decreased and HDL levels increased, while the only risk factor was an increase in LDL levels.

In contrast, those who followed a low-fat diet showed no such improvement in triglycerides or VLDL. There was a slight improvement in HDL, but not as significant as in the low-carb group.

  Low-carb Low-calorie
Triglycerides -40.06 mg/dL -24.40 mg/dL
PAP +2.30 mg/dL +0.89 mg/dL
LDL +0.54 -9.52 mg/dL
VLDL -8.88 mg/dL -4.79 mg/dL

However, after one year, triglycerides and LDL were similar in both groups, and after two years, HDL was similar in both groups.

Hmmm, after 2 years of low-carb or low-fat diet, the groups had the same weight loss, improved triglycerides, LDL and HDL levels, so a tie! Isn’t that so?

Thus, after two years, participants in the low-carb diet had higher HDL levels, meaning that the low-carb diet in this study was slightly better at reducing the risk of cardiovascular disease. As the researchers say: The low-carbohydrate diet group had a greater increase in high-density lipoprotein cholesterol at all time points, by about 23% after 2 years …. A low-carbohydrate diet is associated with a favorable change in cardiovascular disease risk factors over two years.

Figure 2 – Graphs of changes in blood lipids over the 2 years of the study. (Click to enlarge)

Blood pressure and bone density

Sometimes when you do a two-year study, you just add a few tests. Well, it’s two years, and you can get as much information as you want.

There was no difference in hip and spine bone density between the diet participants, and the exercise program did not improve density even after two years. In general, diet (low carb or low fat) and walking do not improve bone density.

Interesting things have happened with the blood pressure.

The diastolic flow rate (the second lowest value on the physician’s chart) was lower after 2 years in those who followed a low-carbohydrate diet than in those who followed a low-fat diet. And those who followed the low-carb diet had lower systolic blood pressure (the first important number your doctor gives you) in the first three months.

Discontinuation of the programme

Two years is a long time to participate in a study, and even if you don’t participate in a study, it’s important to follow the diet to be successful.

Although many critics of the low-carb diet say that people can’t keep it up for long, this two-year study found no difference between the groups in terms of the number of people who dropped out of the diet. The low-carbohydrate and low-fat groups had dropout rates of 42% and 32% (different, but not enough to be considered statistically different).


For years, experts have said that fat is fattening, but it turns out that’s not true. As you can see from this study, it is possible to lose weight without reducing fat. Of course, a 7 kg weight loss in two years is not fantastic.

The next argument was that any weight loss on a low-carb diet is a loss of carbohydrates (glycogen) from the muscles and liver, as well as water, so there will be no long-term weight loss. Again, this claim has been refuted in this and several other studies.

Another argument against low-carb diets is that people may not stick to them for long periods of time because they are too restrictive, but in this study there was little difference in dropout rates between people on low-fat diets and people on low-carb diets.

The latest word from experts is that low-carb diets do not improve cardiovascular disease risk factors such as LDL cholesterol, HDL cholesterol and triglycerides. In this study, subjects who ate the least carbohydrates (in the first three months) had the lowest levels of VLDL cholesterol and triglycerides, while their HDL cholesterol levels rose – all factors that reduce the risk of cardiovascular disease.


The two diets are virtually identical in terms of weight loss and health, with one exception: HDL cholesterol. HDL cholesterol levels were higher in the low-carb group, which argues for a low-carb diet to improve blood lipid profile.

Watch a video summarizing the work of one of the researchers:


Click here to see the sources of information referenced in this article.

  1. Nordmann AJ, Nordmann A, Briel M, Keller U, Yancy WS Jr, Brehm BJ, Bucher HC. Effect of low-carbohydrate and low-fat diets on weight loss and cardiovascular risk factors: a meta-analysis of randomized controlled trials. Arch Intern Med. 2006 Feb 13;166(3):285-93. Review. Erratum in : Arch Intern Med. 2006 Apr 24;166(8):932.


More information

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To view the free courses, click on one of the links below.{“@context”:””,”@type”:”FAQPage”,”mainEntity”:[{“@type”:”Question”,”name”:”What happens if you eat low carb long term?”,”acceptedAnswer”:{“@type”:”Answer”,”text”:” If you eat a low carb diet for an extended period of time, your body will adapt to the lack of carbohydrates and start burning fat for fuel. This is called ketosis. What happens if you eat a low carb diet for a short period of time? If you eat a low carb diet for just a few days, your body will burn mostly fat and protein.”}},{“@type”:”Question”,”name”:”How long does it take for your body to adjust to a low carb diet?”,”acceptedAnswer”:{“@type”:”Answer”,”text”:” It takes about two weeks for your body to adjust to a low carb diet.”}},{“@type”:”Question”,”name”:”Is low carb healthy long term?”,”acceptedAnswer”:{“@type”:”Answer”,”text”:” The short answer is yes. The long answer is that it depends on your goals and how you are eating. If you are trying to lose weight, then a low carb diet can be healthy for the long term. If you are trying to gain weight, then a low carb diet may not be healthy for the long term.”}}]}

Frequently Asked Questions

What happens if you eat low carb long term?

If you eat a low carb diet for an extended period of time, your body will adapt to the lack of carbohydrates and start burning fat for fuel. This is called ketosis. What happens if you eat a low carb diet for a short period of time? If you eat a low carb diet for just a few days, your body will burn mostly fat and protein.

How long does it take for your body to adjust to a low carb diet?

It takes about two weeks for your body to adjust to a low carb diet.

Is low carb healthy long term?

The short answer is yes. The long answer is that it depends on your goals and how you are eating. If you are trying to lose weight, then a low carb diet can be healthy for the long term. If you are trying to gain weight, then a low carb diet may not be healthy for the long term.

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