Welcome back. I missed you. We’re here to finish our discussion on the different types of diets that are out there and to determine which work for weight loss. If you haven’t read part one, we go over what each diet entails and what makes it different from the others. Read it here before reading this so you don’t get lost. Got your favorite reading food ready? Good! Let’s begin.
Low Energy and Very Low Energy Diets
Often, this is the approach many will take when trying to lose weight. They think cutting calories drastically will lead to weight loss. Don’t get me wrong, it absolutely will; however, not all that weight lost will be fat. Up to 25% of the weight lost on these diets can be from muscle aka lean mass1. While many think muscles are only important for bodybuilders, they’re essential for everyone. They help us live our lives injury-free and perform the basic movements that we do without a second thought. Love your muscles. Say thank you by not starving them.
Interestingly, LED & VLED have been able to preserve lean mass on untrained subjects. The research participants were put on a resistance training program and were able to either maintain or increase lean mass2. Keep in mind, these people were untrained and would likely have preserved or built muscle regardless of what happened to them. While interesting, It’s certainly not a reason to try these diets. Being in a chronic (persistent) severe caloric restriction such as LED or VLED can lead to issues arising from low protein intake. Although your calories may consist of mostly protein on these diets, the total amount relative to your body weight matters. On these diets, it’s difficult to acquire that much protein in your diet while staying at such a low amount of calories
Really, one of the only reasons you should be on this diet is if you’re severely obese and you need to drop weight ASAP. Care professionals will often start the patients on a LED or VLED for the first few weeks to begin the loss process. Research shows that this initial restriction actually improves long-term weight loss success3. Over time, however, the drop in calories becomes less aggressive so the patient can slowly increase their metabolism while still dropping weight. They don’t want the patient to be maintaining on the very low calories they started with when they can have them be just as better off on more calories.
Low Fat and Very Low Fat Diets
Low fat diets were all the rage a couple decades ago; but do they actually help with weight loss? Unfortunately, there is little research on VLFD, and none of which cover body composition. These diets are successful in promoting weight loss when intake of fat is reduced from the diet4. Duh. This goes back to what I said in part one. A caloric deficit will usually lead to weight loss.
Although little research has been done on VLFD, there has been some studies that show this diet strategy is difficult to adhere to. When told to consume at most 20% of total calories from fat, subjects were actually consuming around 26-28%, suggesting that it is difficult to stick this diet for varying reasons5. One reason could be that food containing fat is tasty, so people will eat more. Also, lots of foods contain fat, which may make it difficult to reach other macronutrient targets without going over their fat allotment. From this viewpoint, VLFD may not be the best option since you will likely have to go over anyways to satisfy protein and carb intake.
Low Carb and Very Low Carb Diets
There was a recent meta-analysis conducted that did show that LCD diets, especially VLCD, resulted in more fat loss than a normal-level carbohydrate diet6. The findings from this meta-analysis may not be able to be extrapolated (applied to) the general public, as the subjects were obese, and so fat loss was likely regardless of the diet if their calories were being monitored. Still, LCD are very popular and many seem to be able to stick to and enjoy them. I would just say make sure you’re getting in your daily requirement for fiber and fruits and vegetables for the vitamins and minerals if you decide to go low carb. Carbs are still important!
Here we go. A lot of people think that KD is magic and better than other diets because the decreased level of insulin activity. Carbohydrates are the major trigger for insulin to be secreted. For those who don’t know, insulin acts as a “gatekeeper” between your body’s cells and glucose. Once insulin is secreted, it allows for cells to uptake glucose and provide energy to your body. People think that since carbs are not being consumed as much, that less energy and fat is being stored, hence, relying on body fat for energy; however, when put to the test in the lab, this did not hold to be true.
Research shows that, while a KD can induce weight loss, the net amount is not superior to a normal high-carb, energy-restricted diet7. Does this mean that KD doesn’t work? Absolutely not. It simply means that one is not better than the other. This is good news because it allows people flexibility to select what they want and be confident that if they stick to the diet’s protocols, they should see results!
One interesting advantage of a KD is that it may be appetite suppressing. When subjects were allowed to eat as much as they wanted, unrestricted, the KD group had an average decrease of 294 calories consumed per day8. The reason as to why there was a drop in calories is still unknown. Perhaps because more protein was consumed. Protein helps will fullness, and so may have led to the participants getting full quicker.
High Protein Diets
High protein diets have consistently been shown to be beneficial for weight loss. Protein is the most satiating macronutrient. It helps you feel full, and so you (should) eat less than normal, prompting weight loss. But what constitutes a high protein diet and when is it too much? Some work has shown that consuming about two times the Recommended Dietary Allowance (RDA) is optimal for preserving lean mass while simultaneously reducing fat mass9,10. Anything higher has not shown any benefits for this purpose11. Double the RDA amount is roughly 1.6 grams/kilogram bodyweight (0.7 grams/pound bodyweight).
All of these diet strategies can work for losing weight. It is up to you to decide which one you like and what you will stick to. Remember, it’s not the diet that’s going to trigger weight loss, it’s the caloric deficit. That is what matters when we’re concerned with losing weight. Personally, I would not go with LED, VLED, or VLFD. These diets are going to be difficult to stick to, and/or you may not acquire all the necessary nutrients that you need in the proper amounts. I do not have an issue with the other strategies as long as they are being adhered to and you are enjoying the process. Once again, dieting should not be a hellish process if you’re simply trying to lose some weight for an upcoming event or you’re starting a journey to improve your health.
Adopt a healthy, happy relationship with food, and you’ll find that losing weight can be enjoyable and your life does not have to be centered around food! Still have questions? Let me know in the comments below! Thanks for reading! Share this with others who think there are magical diets!
1Saris W. Very-low-calorie diets and sustained weight loss. Obes Res. 2001;9 Suppl 4:295S–301S.
2Bryner R, Ullrich I, Sauers J, Donley D, Hornsby G, Kolar M, et al. Effects of resistance vs. aerobic training combined with an 800 calorie liquid diet on lean body mass and resting metabolic rate. J Am Coll Nutr. 1999;18(2):115–21.
3Nackers L, Ross K, Perri M. The association between rate of initial weight loss and long-term success in obesity treatment: does slow and steady win the race? Int J Behav Med. 2010;17(3):161–7.
4Hooper LAA, Bunn D, Brown T, Summerbell CD, Skeaff CM. Effects of total fat intake on body weight. Cochrane Database Syst Rev. 2015;7(8):CD011834.
5De Souza R, Bray G, Carey V, Hall K, LeBoff M, Loria C, et al. Effects of 4 weight-loss diets differing in fat, protein, and carbohydrate on fat mass, lean mass, visceral adipose tissue, and hepatic fat: results from the POUNDS LOST trial. Am J Clin Nutr. 2012;95(3):614–25.
6Hashimoto Y, Fukuda T, Oyabu C, Tanaka M, Asano M, Yamazaki M, et al. Impact of low-carbohydrate diet on body composition: meta-analysis of randomized controlled studies. Obes Rev. 2016;17(6):499–509.
7Hall K, Chen K, Guo J, Lam Y, Leibel R, Mayer L, et al. Energy expenditure and body composition changes after an isocaloric ketogenic diet in overweight and obese men. Am J Clin Nutr. 2016;104(2):324–33.
8Johnstone A, Horgan G, Murison S, Bremner D, Lobley G. Effects of a high-protein ketogenic diet on hunger, appetite, and weight loss in obese men feeding ad libitum. Am J Clin Nutr. 2008;87(1):44–55.
9Layman D, Evans E, Erickson D, Seyler J, Weber J, Bagshaw D, et al. A moderate-protein diet produces sustained weight loss and long-term changes in body composition and blood lipids in obese adults. J Nutr. 2009;139(3):514–21.
10Layman D, Evans E, Baum J, Seyler J, Erickson D, Boileau R. Dietary protein and exercise have additive effects on body composition during weight loss in adult women. J Nutr. 2005;135(8):1903–10.
11Pasiakos S, Cao J, Margolis L, Sauter E, Whigham L, McClung J, et al. Effects of high-protein diets on fat-free mass and muscle protein synthesis following weight loss: a randomized controlled trial. FASEB J. 2013;27(9):3837–47.