Ask the RD · Nutrition · weight loss

Ask the RD: Weight Loss Confusion 

Q: I am getting married in August and I started doing crossfit to get in good shape but when I read about nutrition there are so many different views on what you should do. I am currently using My Fitness Pal to calorie count and set my my carbs at 35%, protein at 35%, and fats at 30%. I am 6’1″ and weigh 250 lb. I am trying to lose 2 pounds a week. I do crossfit 3 times a weekend. 

Is this a good plan or should I be eating more calories to be gaining muscle? Or calorie cycling? My brain is spinning with all the information on the Internet. I didn’t know if you could point me in the right direction. Any help is appreciated.


A: Hi Steve,

First off, congratulations on your engagement! 

Secondly, it’s very easy to feel confused with all of the information available on nutrition, various diets, and weight loss these days. I get asked about that is the “best diet” often, and to be honest, any diet plan can work if in some way it creates a caloric deficit. This being said, the recommendations I prefer to give help create a lifestyle change that can be sustained. 

Your goal is weight loss and so you’re going to need to create a calorie deficit. I think you’re off to a good start by using My Fitness Pal and tracking your intake. Just based on some simple calculations using the height and weight you gave me, theoretically your body needs about 3400 calories a day to maintain weight. If you’ve been tracking for a good period of time, you’ll know if you’re anywhere around that. If you’re just getting started with tracking, you can use this as an estimate to create your deficit from. I recommend not to be too quick in dropping calories though, which can lead to unnecessary metabolism slowing and can make it hard to recover from intense workouts like cross fit. 

Based on your numbers, I recommend starting out at 3000 calories/day. Give that a try for at least two weeks and see how your weight changes. If you’ve lost weight after a couple weeks, keep it at 3000 until you’re losing less than a pound a week. As weight loss slows, decrease it by 100-200 calories at a time, again giving your body about 2 weeks to respond before making any changes. 

As far as protein/carb/fat ratios go, the breakdown you’ve been using of 35% carbs, 35 protein, 30 fat is fine. I generally start clients at 40/30/30. Paleo diets tend to be very popular amongst crossfitters, which may or may not be promoted at your gym. I think the paleo diet is great, however it can easy turn into a low-carb/high-fat diet. Even if your goal is weight loss, I think it’s still important to eat a moderate to high amount of carbs in order to maintain energy levels and keep metabolism high. Keeping fat low to moderate (20-30%) will help support weight loss. 

Calorie and/or carb cycling can be a good technique to try if you hit a weight loss plateau but I wouldn’t recommend it to start out with, not until you see how your body responds to a general calorie deficit.

Speaking to your concern about gaining muscle- It’s possible to gain muscle while losing body fat, but it’s challenging. Building muscle requires at least a mild calorie surplus. If your goal is to lose body fat, I would focus on that first. Once you get to your desired weight/level of leanness, you can shift into “reverse dieting” in which you slowly add back calories to support muscle growth.

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